Broad economic benefits of freight transportation infrastructure improvement.

Science.gov (United States)

2012-06-01

This project strives to introduce a novel way to quantify the broad re-organization benefits associated with an : improvement in the freight infrastructure. Using the approach based on 1) the technique known as Field of Influence, and : 2) RAS adjust...

Socioeconomic evaluation of broad-scale land management strategies.

Science.gov (United States)

Lisa K. Crone; Richard W. Haynes

2001-01-01

This paper examines the socioeconomic effects of alternative management strategies for Forest Service and Bureau of Land Management lands in the interior Columbia basin. From a broad-scale perspective, there is little impact or variation between alternatives in terms of changes in total economic activity or social conditions in the region. However, adopting a finer...

Small-scale Scheimpflug lidar for aerosol extinction coefficient and vertical atmospheric transmittance detection.

Science.gov (United States)

Sun, Guodong; Qin, Laian; Hou, Zaihong; Jing, Xu; He, Feng; Tan, Fengfu; Zhang, Silong

2018-03-19

In this paper, a new prototypical Scheimpflug lidar capable of detecting the aerosol extinction coefficient and vertical atmospheric transmittance at 1 km above the ground is described. The lidar system operates at 532 nm and can be used to detect aerosol extinction coefficients throughout an entire day. Then, the vertical atmospheric transmittance can be determined from the extinction coefficients with the equation of numerical integration in this area. CCD flat fielding of the image data is used to mitigate the effects of pixel sensitivity variation. An efficient method of two-dimensional wavelet transform according to a local threshold value has been proposed to reduce the Gaussian white noise in the lidar signal. Furthermore, a new iteration method of backscattering ratio based on genetic algorithm is presented to calculate the aerosol extinction coefficient and vertical atmospheric transmittance. Some simulations are performed to reduce the different levels of noise in the simulated signal in order to test the precision of the de-noising method and inversion algorithm. The simulation result shows that the root-mean-square errors of extinction coefficients are all less than 0.02 km -1 , and that the relative errors of the atmospheric transmittance between the model and inversion data are below 0.56% for all cases. The feasibility of the instrument and the inversion algorithm have also been verified by an optical experiment. The average relative errors of aerosol extinction coefficients between the Scheimpflug lidar and the conventional backscattering elastic lidar are 3.54% and 2.79% in the full overlap heights of two time points, respectively. This work opens up new possibilities of using a small-scale Scheimpflug lidar system for the remote sensing of atmospheric aerosols.

Generation of a Broad-Group HTGR Library for Use with SCALE

International Nuclear Information System (INIS)

Ellis, Ronald James; Lee, Deokjung; Wiarda, Dorothea; Williams, Mark L.; Mertyurek, Ugur

2012-01-01

With current and ongoing interest in high temperature gas reactors (HTGRs), the U.S. Nuclear Regulatory Commission (NRC) anticipates the need for nuclear data libraries appropriate for use in applications for modeling, assessing, and analyzing HTGR reactor physics and operating behavior. The objective of this work was to develop a broad-group library suitable for production analyses with SCALE for HTGR applications. Several interim libraries were generated from SCALE fine-group 238- and 999-group libraries, and the final broad-group library was created from Evaluated Nuclear Data File/B Version ENDF/B-VII Release 0 cross-section evaluations using new ORNL methodologies with AMPX, SCALE, and other codes. Furthermore, intermediate resonance (IR) methods were applied to the HTGR broadgroup library, and lambda factors and f-factors were incorporated into the library s nuclear data files. A new version of the SCALE BONAMI module named BONAMI-IR was developed to process the IR data in the new library and, thus, eliminate the need for the CENTRM/PMC modules for resonance selfshielding. This report documents the development of the HTGR broad-group nuclear data library and the results of test and benchmark calculations using the new library with SCALE. The 81-group library is shown to model HTGR cases with similar accuracy to the SCALE 238-group library but with significantly faster computational times due to the reduced number of energy groups and the use of BONAMI-IR instead of BONAMI/CENTRM/PMC for resonance self-shielding calculations.

Association of extinction risk of saproxylic beetles with ecological degradation of forests in Europe.

Science.gov (United States)

Seibold, Sebastian; Brandl, Roland; Buse, Jörn; Hothorn, Torsten; Schmidl, Jürgen; Thorn, Simon; Müller, Jörg

2015-04-01

To reduce future loss of biodiversity and to allocate conservation funds effectively, the major drivers behind large-scale extinction processes must be identified. A promising approach is to link the red-list status of species and specific traits that connect species of functionally important taxa or guilds to resources they rely on. Such traits can be used to detect the influence of anthropogenic ecosystem changes and conservation efforts on species, which allows for practical recommendations for conservation. We modeled the German Red List categories as an ordinal index of extinction risk of 1025 saproxylic beetles with a proportional-odds linear mixed-effects model for ordered categorical responses. In this model, we estimated fixed effects for intrinsic traits characterizing species biology, required resources, and distribution with phylogenetically correlated random intercepts. The model also allowed predictions of extinction risk for species with no red-list category. Our model revealed a higher extinction risk for lowland and large species as well as for species that rely on wood of large diameter, broad-leaved trees, or open canopy. These results mirror well the ecological degradation of European forests over the last centuries caused by modern forestry, that is the conversion of natural broad-leaved forests to dense conifer-dominated forests and the loss of old growth and dead wood. Therefore, conservation activities aimed at saproxylic beetles in all types of forests in Central and Western Europe should focus on lowlands, and habitat management of forest stands should aim at increasing the amount of dead wood of large diameter, dead wood of broad-leaved trees, and dead wood in sunny areas. © 2014 Society for Conservation Biology.

Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility.

Science.gov (United States)

Fischer, Valentin; Bardet, Nathalie; Benson, Roger B J; Arkhangelsky, Maxim S; Friedman, Matt

2016-03-08

Despite their profound adaptations to the aquatic realm and their apparent success throughout the Triassic and the Jurassic, ichthyosaurs became extinct roughly 30 million years before the end-Cretaceous mass extinction. Current hypotheses for this early demise involve relatively minor biotic events, but are at odds with recent understanding of the ichthyosaur fossil record. Here, we show that ichthyosaurs maintained high but diminishing richness and disparity throughout the Early Cretaceous. The last ichthyosaurs are characterized by reduced rates of origination and phenotypic evolution and their elevated extinction rates correlate with increased environmental volatility. In addition, we find that ichthyosaurs suffered from a profound Early Cenomanian extinction that reduced their ecological diversity, likely contributing to their final extinction at the end of the Cenomanian. Our results support a growing body of evidence revealing that global environmental change resulted in a major, temporally staggered turnover event that profoundly reorganized marine ecosystems during the Cenomanian.

Decline and local extinction of Fucales in French Riviera: the harbinger of future extinctions?

Directory of Open Access Journals (Sweden)

T. THIBAUT

2014-03-01

Full Text Available The French Riviera is one of the Mediterranean areas that has been longest and most thoroughly impacted by human activities. Fucales are long-lived, large-sized brown algae that constitute a good model for studying human impact on species diversity. We gathered all historical data (literature and herbarium vouchers, since the early 19th century, to reconstruct their distribution. The current distribution was established from a 7-year (2007-2013 survey of the 212-km shoreline (1/2 500 map, by means of boating, snorkelling and scuba diving. Overall, 18 taxa of Cystoseira and Sargassum have been reported. Upon comparison with historical data, 5 taxa were no longer observed (C. elegans, C. foeniculacea f. latiramosa, C. squarrosa, C. spinosa var. spinosa and S. hornschuchii while C. jabukae, previously unrecorded, was observed. In addition to these  taxa, probably extinct at a local scale, some taxa had suffered a dramatic decline (C. barbata f. barbata, C. crinita, C. spinosa var. compressa and S. acinarium or become nearly extinct (C. foeniculacea f. tenuiramosa. Three of them, which played in the past significant functional roles in coastal communities, can be considered as functionally extinct. Possible causes of decline and local extinction are discussed. A similar situation has already been reported, although at a much more local scale, in a variety of Mediterranean localities. The question therefore arises about the status of Fucales species in the Mediterranean: are some species on the brink of extinction? Is their extinction at the scale of the French Riviera the harbinger of their extinction Mediterranean–wide?

Updating Procedures Can Reorganize the Neural Circuit Supporting a Fear Memory.

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Kwapis, Janine L; Jarome, Timothy J; Ferrara, Nicole C; Helmstetter, Fred J

2017-07-01

Established memories undergo a period of vulnerability following retrieval, a process termed 'reconsolidation.' Recent work has shown that the hypothetical process of reconsolidation is only triggered when new information is presented during retrieval, suggesting that this process may allow existing memories to be modified. Reconsolidation has received increasing attention as a possible therapeutic target for treating disorders that stem from traumatic memories, yet little is known about how this process changes the original memory. In particular, it is unknown whether reconsolidation can reorganize the neural circuit supporting an existing memory after that memory is modified with new information. Here, we show that trace fear memory undergoes a protein synthesis-dependent reconsolidation process following exposure to a single updating trial of delay conditioning. Further, this reconsolidation-dependent updating process appears to reorganize the neural circuit supporting the trace-trained memory, so that it better reflects the circuit supporting delay fear. Specifically, after a trace-to-delay update session, the amygdala is now required for extinction of the updated memory but the retrosplenial cortex is no longer required for retrieval. These results suggest that updating procedures could be used to force a complex, poorly defined memory circuit to rely on a better-defined neural circuit that may be more amenable to behavioral or pharmacological manipulation. This is the first evidence that exposure to new information can fundamentally reorganize the neural circuit supporting an existing memory.

Biological extinction in earth history

Science.gov (United States)

Raup, D. M.

1986-01-01

Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

Biological Extinction in Earth History

Science.gov (United States)

Raup, David M.

1986-03-01

Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

Adaptive radiation of multituberculate mammals before the extinction of dinosaurs.

Science.gov (United States)

Wilson, Gregory P; Evans, Alistair R; Corfe, Ian J; Smits, Peter D; Fortelius, Mikael; Jernvall, Jukka

2012-03-14

The Cretaceous-Paleogene mass extinction approximately 66 million years ago is conventionally thought to have been a turning point in mammalian evolution. Prior to that event and for the first two-thirds of their evolutionary history, mammals were mostly confined to roles as generalized, small-bodied, nocturnal insectivores, presumably under selection pressures from dinosaurs. Release from these pressures, by extinction of non-avian dinosaurs at the Cretaceous-Paleogene boundary, triggered ecological diversification of mammals. Although recent individual fossil discoveries have shown that some mammalian lineages diversified ecologically during the Mesozoic era, comprehensive ecological analyses of mammalian groups crossing the Cretaceous-Paleogene boundary are lacking. Such analyses are needed because diversification analyses of living taxa allow only indirect inferences of past ecosystems. Here we show that in arguably the most evolutionarily successful clade of Mesozoic mammals, the Multituberculata, an adaptive radiation began at least 20 million years before the extinction of non-avian dinosaurs and continued across the Cretaceous-Paleogene boundary. Disparity in dental complexity, which relates to the range of diets, rose sharply in step with generic richness and disparity in body size. Moreover, maximum dental complexity and body size demonstrate an adaptive shift towards increased herbivory. This dietary expansion tracked the ecological rise of angiosperms and suggests that the resources that were available to multituberculates were relatively unaffected by the Cretaceous-Paleogene mass extinction. Taken together, our results indicate that mammals were able to take advantage of new ecological opportunities in the Mesozoic and that at least some of these opportunities persisted through the Cretaceous-Paleogene mass extinction. Similar broad-scale ecomorphological inventories of other radiations may help to constrain the possible causes of mass extinctions.

Broad-scale small-world network topology induces optimal synchronization of flexible oscillators

International Nuclear Information System (INIS)

Markovič, Rene; Gosak, Marko; Marhl, Marko

2014-01-01

The discovery of small-world and scale-free properties of many man-made and natural complex networks has attracted increasing attention. Of particular interest is how the structural properties of a network facilitate and constrain its dynamical behavior. In this paper we study the synchronization of weakly coupled limit-cycle oscillators in dependence on the network topology as well as the dynamical features of individual oscillators. We show that flexible oscillators, characterized by near zero values of divergence, express maximal correlation in broad-scale small-world networks, whereas the non-flexible (rigid) oscillators are best correlated in more heterogeneous scale-free networks. We found that the synchronization behavior is governed by the interplay between the networks global efficiency and the mutual frequency adaptation. The latter differs for flexible and rigid oscillators. The results are discussed in terms of evolutionary advantages of broad-scale small-world networks in biological systems

Extinction of mammalian populations in conservation units of the Brazilian Cerrado by inbreeding depression in stochastic environments

OpenAIRE

Silva, Marcel Müller Fernandes Pereira da; Diniz-Filho, José Alexandre Felizola

2008-01-01

Despite methodological and theoretical advances in conservation genetics, data on genetic variation on broad regional spatial scales are still scarce, leading conservation planners to use general heuristic or simulation models for an integrated analysis of genetic, demographic and landscape parameters. Here, we extended previous results by evaluating spatial patterns of extinction by inbreeding depression under stochastic variation of environments for mammalian populations in 31 conservation ...

Current extinction rates of reptiles and amphibians.

Science.gov (United States)

Alroy, John

2015-10-20

There is broad concern that a mass extinction of amphibians and reptiles is now underway. Here I apply an extremely conservative Bayesian method to estimate the number of recent amphibian and squamate extinctions in nine important tropical and subtropical regions. The data stem from a combination of museum collection databases and published site surveys. The method computes an extinction probability for each species by considering its sighting frequency and last sighting date. It infers hardly any extinction when collection dates are randomized and it provides underestimates when artificial extinction events are imposed. The method also appears to be insensitive to trends in sampling; therefore, the counts it provides are absolute minimums. Extinctions or severe population crashes have accumulated steadily since the 1970s and 1980s, and at least 3.1% of frog species have already disappeared. Based on these data and this conservative method, the best estimate of the global grand total is roughly 200 extinctions. Consistent with previous results, frog losses are heavy in Latin America, which has been greatly affected by the pathogenic chytrid fungus Batrachochytrium dendrobatidis. Extinction rates are now four orders-of-magnitude higher than background, and at least another 6.9% of all frog species may be lost within the next century, even if there is no acceleration in the growth of environmental threats.

Near-memory data reorganization engine

Science.gov (United States)

Gokhale, Maya; Lloyd, G. Scott

2018-05-08

A memory subsystem package is provided that has processing logic for data reorganization within the memory subsystem package. The processing logic is adapted to reorganize data stored within the memory subsystem package. In some embodiments, the memory subsystem package includes memory units, a memory interconnect, and a data reorganization engine ("DRE"). The data reorganization engine includes a stream interconnect and DRE units including a control processor and a load-store unit. The control processor is adapted to execute instructions to control a data reorganization. The load-store unit is adapted to process data move commands received from the control processor via the stream interconnect for loading data from a load memory address of a memory unit and storing data to a store memory address of a memory unit.

Large-Scale Functional Brain Network Reorganization During Taoist Meditation.

Science.gov (United States)

Jao, Tun; Li, Chia-Wei; Vértes, Petra E; Wu, Changwei Wesley; Achard, Sophie; Hsieh, Chao-Hsien; Liou, Chien-Hui; Chen, Jyh-Horng; Bullmore, Edward T

2016-02-01

Meditation induces a distinct and reversible mental state that provides insights into brain correlates of consciousness. We explored brain network changes related to meditation by graph theoretical analysis of resting-state functional magnetic resonance imaging data. Eighteen Taoist meditators with varying levels of expertise were scanned using a within-subjects counterbalanced design during resting and meditation states. State-related differences in network topology were measured globally and at the level of individual nodes and edges. Although measures of global network topology, such as small-worldness, were unchanged, meditation was characterized by an extensive and expertise-dependent reorganization of the hubs (highly connected nodes) and edges (functional connections). Areas of sensory cortex, especially the bilateral primary visual and auditory cortices, and the bilateral temporopolar areas, which had the highest degree (or connectivity) during the resting state, showed the biggest decrease during meditation. Conversely, bilateral thalamus and components of the default mode network, mainly the bilateral precuneus and posterior cingulate cortex, had low degree in the resting state but increased degree during meditation. Additionally, these changes in nodal degree were accompanied by reorganization of anatomical orientation of the edges. During meditation, long-distance longitudinal (antero-posterior) edges increased proportionally, whereas orthogonal long-distance transverse (right-left) edges connecting bilaterally homologous cortices decreased. Our findings suggest that transient changes in consciousness associated with meditation introduce convergent changes in the topological and spatial properties of brain functional networks, and the anatomical pattern of integration might be as important as the global level of integration when considering the network basis for human consciousness.

Global ocean conveyor lowers extinction risk in the deep sea

Science.gov (United States)

Henry, Lea-Anne; Frank, Norbert; Hebbeln, Dierk; Wienberg, Claudia; Robinson, Laura; van de Flierdt, Tina; Dahl, Mikael; Douarin, Mélanie; Morrison, Cheryl L.; López Correa, Matthias; Rogers, Alex D.; Ruckelshausen, Mario; Roberts, J. Murray

2014-06-01

General paradigms of species extinction risk are urgently needed as global habitat loss and rapid climate change threaten Earth with what could be its sixth mass extinction. Using the stony coral Lophelia pertusa as a model organism with the potential for wide larval dispersal, we investigated how the global ocean conveyor drove an unprecedented post-glacial range expansion in Earth's largest biome, the deep sea. We compiled a unique ocean-scale dataset of published radiocarbon and uranium-series dates of fossil corals, the sedimentary protactinium-thorium record of Atlantic meridional overturning circulation (AMOC) strength, authigenic neodymium and lead isotopic ratios of circulation pathways, and coral biogeography, and integrated new Bayesian estimates of historic gene flow. Our compilation shows how the export of Southern Ocean and Mediterranean waters after the Younger Dryas 11.6 kyr ago simultaneously triggered two dispersal events in the western and eastern Atlantic respectively. Each pathway injected larvae from refugia into ocean currents powered by a re-invigorated AMOC that led to the fastest postglacial range expansion ever recorded, covering 7500 km in under 400 years. In addition to its role in modulating global climate, our study illuminates how the ocean conveyor creates broad geographic ranges that lower extinction risk in the deep sea.

Nile damming as plausible cause of extinction and drop in abundance of deep-sea shrimp in the western Mediterranean over broad spatial scales

Science.gov (United States)

Cartes, J. E.; Maynou, F.; Fanelli, E.

2011-11-01

Greatly increased retention of flow in Nile River reservoirs was initiated in 1964, after completion of the Aswan High Dam, which induced important oceanographic changes in the Mediterranean Sea, including deep waters (below a depth of 150 m). Based on an analysis of data series starting in the 1940s/1950s, the giant red shrimp Aristaeomorpha foliacea has become locally extinct off of the Catalonian coasts (and elsewhere in the northwestern Mediterranean) at depths of 400-900 m, with a simultaneous and significant drop in the catches of red shrimp, Aristeus antennatus, in the second half of the 1960s. The extinction and sharp decline of deep-shrimp populations off Catalonian coast (at ca. 3200 km westwards from Nile Delta) followed the 1964 drop in Nile discharge with a delay of ca. 3-5 yrs (breakpoint analysis applied to data series). The breakpoints detected in the second half of 1960s both in Nile runoff and shrimps’ abundance were independent of climatic events in the study area (e.g. changes in NAO) and occurred before the increase in fishing effort off Catalonian coasts (breakpoint in 1973-1974). The Levantine Intermediate Water (LIW), inhabited by A. foliacea in the western Basin, had significant temperature (T) and salinity (S) increases in the 1950-1970 period, and Nile damming has contributed about 45% of the total S increase of Western Mediterranean deep-water masses from the 1960s to the late 1990s (Skliris and Lascaratos, 2004). This had to increase, for instance, LIW salinity at its formation site in the eastern Mediterranean. Nile damming was probably a triggering factor for the extinction/drop in abundance of deep-sea shrimp off Catalonian coasts.

Artificial light at night confounds broad-scale habitat use by migrating birds

Science.gov (United States)

McLaren, James D.; Buler, Jeffrey J.; Schreckengost, Tim; Smolinsky, Jaclyn A.; Boone, Matthew; van Loon, E. Emiel; Dawson, Deanna K.; Walters, Eric L.

2018-01-01

With many of the world's migratory bird populations in alarming decline, broad-scale assessments of responses to migratory hazards may prove crucial to successful conservation efforts. Most birds migrate at night through increasingly light-polluted skies. Bright light sources can attract airborne migrants and lead to collisions with structures, but might also influence selection of migratory stopover habitat and thereby acquisition of food resources. We demonstrate, using multi-year weather radar measurements of nocturnal migrants across the northeastern U.S., that autumnal migrant stopover density increased at regional scales with proximity to the brightest areas, but decreased within a few kilometers of brightly-lit sources. This finding implies broad-scale attraction to artificial light while airborne, impeding selection for extensive forest habitat. Given that high-quality stopover habitat is critical to successful migration, and hindrances during migration can decrease fitness, artificial lights present a potentially heightened conservation concern for migratory bird populations.

Predicting extinction rates in stochastic epidemic models

International Nuclear Information System (INIS)

Schwartz, Ira B; Billings, Lora; Dykman, Mark; Landsman, Alexandra

2009-01-01

We investigate the stochastic extinction processes in a class of epidemic models. Motivated by the process of natural disease extinction in epidemics, we examine the rate of extinction as a function of disease spread. We show that the effective entropic barrier for extinction in a susceptible–infected–susceptible epidemic model displays scaling with the distance to the bifurcation point, with an unusual critical exponent. We make a direct comparison between predictions and numerical simulations. We also consider the effect of non-Gaussian vaccine schedules, and show numerically how the extinction process may be enhanced when the vaccine schedules are Poisson distributed

Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates.

Science.gov (United States)

Motani, Ryosuke; Jiang, Da-Yong; Tintori, Andrea; Ji, Cheng; Huang, Jian-Dong

2017-05-17

The fossil record of a major clade often starts after a mass extinction even though evolutionary rates, molecular or morphological, suggest its pre-extinction emergence (e.g. squamates, placentals and teleosts). The discrepancy is larger for older clades, and the presence of a time-scale-dependent methodological bias has been suggested, yet it has been difficult to avoid the bias using Bayesian phylogenetic methods. This paradox raises the question of whether ecological vacancies, such as those after mass extinctions, prompt the radiations. We addressed this problem by using a unique temporal characteristic of the morphological data and a high-resolution stratigraphic record, for the oldest clade of Mesozoic marine reptiles, Ichthyosauromorpha. The evolutionary rate was fastest during the first few million years of ichthyosauromorph evolution and became progressively slower over time, eventually becoming six times slower. Using the later slower rates, estimates of divergence time become excessively older. The fast, initial rate suggests the emergence of ichthyosauromorphs after the end-Permian mass extinction, matching an independent result from high-resolution stratigraphic confidence intervals. These reptiles probably invaded the sea as a new ecosystem was formed after the end-Permian mass extinction. Lack of information on early evolution biased Bayesian clock rates. © 2017 The Author(s).

Mass Extinctions and Biosphere-Geosphere Stability

Science.gov (United States)

Rothman, Daniel; Bowring, Samuel

2015-04-01

Five times in the past 500 million years, mass extinctions have resulted in the loss of greater than three-fourths of living species. Each of these events is associated with significant environmental change recorded in the carbon-isotopic composition of sedimentary rocks. There are also many such environmental events in the geologic record that are not associated with mass extinctions. What makes them different? Two factors appear important: the size of the environmental perturbation, and the time scale over which it occurs. We show that the natural perturbations of Earth's carbon cycle during the past 500 million years exhibit a characteristic rate of change over two orders of magnitude in time scale. This characteristic rate is consistent with the maximum rate that limits quasistatic (i.e., near steady-state) evolution of the carbon cycle. We identify this rate with marginal stability, and show that mass extinctions occur on the fast, unstable side of the stability boundary. These results suggest that the great extinction events of the geologic past, and potentially a "sixth extinction" associated with modern environmental change, are characterized by common mechanisms of instability.

Galactic dust and extinction

International Nuclear Information System (INIS)

Lyngaa, G.

1979-01-01

The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards l=50 0 than towards l=230 0 . On the smaller scale, much of the dust responsible for extinction is situated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars. (Auth.)

Broad-scale Population Genetics of the Host Sea Anemone, Heteractis magnifica

KAUST Repository

Emms, Madeleine

2015-12-01

Broad-scale population genetics can reveal population structure across an organism’s entire range, which can enable us to determine the most efficient population-wide management strategy depending on levels of connectivity. Genetic variation and differences in genetic diversity on small-scales have been reported in anemones, but nothing is known about their broad-scale population structure, including that of “host” anemone species, which are increasingly being targeted in the aquarium trade. In this study, microsatellite markers were used as a tool to determine the population structure of a sessile, host anemone species, Heteractis magnifica, across the Indo-Pacific region. In addition, two rDNA markers were used to identify Symbiodinium from the samples, and phylogenetic analyses were used to measure diversity and geographic distribution of Symbiodinium across the region. Significant population structure was identified in H. magnifica across the Indo-Pacific, with at least three genetic breaks, possibly the result of factors such as geographic distance, geographic isolation and environmental variation. Symbiodinium associations were also affected by environmental variation and supported the geographic isolation of some regions. These results suggests that management of H. magnifica must be implemented on a local scale, due to the lack of connectivity between clusters. This study also provides further evidence for the combined effects of geographic distance and environmental distance in explaining genetic variance.

Progress to extinction: increased specialisation causes the demise of animal clades.

Science.gov (United States)

Raia, P; Carotenuto, F; Mondanaro, A; Castiglione, S; Passaro, F; Saggese, F; Melchionna, M; Serio, C; Alessio, L; Silvestro, D; Fortelius, M

2016-08-10

Animal clades tend to follow a predictable path of waxing and waning during their existence, regardless of their total species richness or geographic coverage. Clades begin small and undifferentiated, then expand to a peak in diversity and range, only to shift into a rarely broken decline towards extinction. While this trajectory is now well documented and broadly recognised, the reasons underlying it remain obscure. In particular, it is unknown why clade extinction is universal and occurs with such surprising regularity. Current explanations for paleontological extinctions call on the growing costs of biological interactions, geological accidents, evolutionary traps, and mass extinctions. While these are effective causes of extinction, they mainly apply to species, not clades. Although mass extinctions is the undeniable cause for the demise of a sizeable number of major taxa, we show here that clades escaping them go extinct because of the widespread tendency of evolution to produce increasingly specialised, sympatric, and geographically restricted species over time.

Progress to extinction: increased specialisation causes the demise of animal clades

Science.gov (United States)

Raia, P.; Carotenuto, F.; Mondanaro, A.; Castiglione, S.; Passaro, F.; Saggese, F.; Melchionna, M.; Serio, C.; Alessio, L.; Silvestro, D.; Fortelius, M.

2016-08-01

Animal clades tend to follow a predictable path of waxing and waning during their existence, regardless of their total species richness or geographic coverage. Clades begin small and undifferentiated, then expand to a peak in diversity and range, only to shift into a rarely broken decline towards extinction. While this trajectory is now well documented and broadly recognised, the reasons underlying it remain obscure. In particular, it is unknown why clade extinction is universal and occurs with such surprising regularity. Current explanations for paleontological extinctions call on the growing costs of biological interactions, geological accidents, evolutionary traps, and mass extinctions. While these are effective causes of extinction, they mainly apply to species, not clades. Although mass extinctions is the undeniable cause for the demise of a sizeable number of major taxa, we show here that clades escaping them go extinct because of the widespread tendency of evolution to produce increasingly specialised, sympatric, and geographically restricted species over time.

The three-quarter power scaling of extinction risk in Late Pleistocene mammals, and a new theory of the size selectivity of extinction

NARCIS (Netherlands)

Polishchuk, L.

2010-01-01

Questions: What is the pattern of body mass versus extinction risk in the Late Pleistocene extinctions of mammals, both qualitatively and quantitatively? Are there patterns that relate extinction risk to the well-known allometries of body mass with population density or population growth rate?

Biological hierarchies and the nature of extinction.

Science.gov (United States)

Congreve, Curtis R; Falk, Amanda R; Lamsdell, James C

2018-05-01

Hierarchy theory recognises that ecological and evolutionary units occur in a nested and interconnected hierarchical system, with cascading effects occurring between hierarchical levels. Different biological disciplines have routinely come into conflict over the primacy of different forcing mechanisms behind evolutionary and ecological change. These disconnects arise partly from differences in perspective (with some researchers favouring ecological forcing mechanisms while others favour developmental/historical mechanisms), as well as differences in the temporal framework in which workers operate. In particular, long-term palaeontological data often show that large-scale (macro) patterns of evolution are predominantly dictated by shifts in the abiotic environment, while short-term (micro) modern biological studies stress the importance of biotic interactions. We propose that thinking about ecological and evolutionary interactions in a hierarchical framework is a fruitful way to resolve these conflicts. Hierarchy theory suggests that changes occurring at lower hierarchical levels can have unexpected, complex effects at higher scales due to emergent interactions between simple systems. In this way, patterns occurring on short- and long-term time scales are equally valid, as changes that are driven from lower levels will manifest in different forms at higher levels. We propose that the dual hierarchy framework fits well with our current understanding of evolutionary and ecological theory. Furthermore, we describe how this framework can be used to understand major extinction events better. Multi-generational attritional loss of reproductive fitness (MALF) has recently been proposed as the primary mechanism behind extinction events, whereby extinction is explainable solely through processes that result in extirpation of populations through a shutdown of reproduction. While not necessarily explicit, the push to explain extinction through solely population-level dynamics

Experimental evidence of reorganizing landscape under changing climatic forcing

Science.gov (United States)

Singh, A.; Tejedor, A.; Zaliapin, I. V.; Reinhardt, L.; Foufoula-Georgiou, E.

2015-12-01

Quantification of the dynamics of landscape reorganization under changing climatic forcing is important to understand geomorphic transport laws under transient conditions, assess response of landscapes to external perturbations for future predictive modeling, and for interpreting past climate from stratigraphic record. For such an analysis, however, real landscape observations are limited. To this end, a series of controlled laboratory experiments on evolving landscape were conducted at the St. Anthony Falls laboratory at the University of Minnesota. High resolution elevation data at a temporal resolution of 5 mins and spatial resolution of 0.5 mm were collected as the landscape approached steady state (constant uplift and precipitation rate) and in the transient state (under the same uplift and 5 times precipitation rate). Our results reveal rapid topographic re-organization under a five-fold increase in precipitation with the fluvial regime encroaching into the previously debris dominated regime, widening and aggradation of channels and valleys, and accelerated erosion happening at hillslope scales. To better understand the initiation of the observed reorganization, we perform a connectivity and clustering analysis of the erosional and depositional events, showing strikingly different spatial patterns on landscape evolution under steady-state (SS) and transient-state (TS), even when the time under SS is renormalized to match the total volume of eroded and deposited sediment in TS. Our results suggest a regime shift in the behavior of transport processes on the landscape at the intermediate scales i.e., from supply-limited to transport-limited.

VLT/X-shooter GRBs: Individual extinction curves of star-forming regions★

Science.gov (United States)

Zafar, T.; Watson, D.; Møller, P.; Selsing, J.; Fynbo, J. PU; Schady, P.; Wiersema, K.; Levan, A. J.; Heintz, K. E.; Postigo, A. de Ugarte; D'Elia, V.; Jakobsson, P.; Bolmer, J.; Japelj, J.; Covino, S.; Gomboc, A.; Cano, Z.

2018-05-01

The extinction profiles in Gamma-Ray Burst (GRB) afterglow spectral energy distributions (SEDs) are usually described by the Small Magellanic Cloud (SMC)-type extinction curve. In different empirical extinction laws, the total-to-selective extinction, RV, is an important quantity because of its relation to dust grain sizes and compositions. We here analyse a sample of 17 GRBs (0.34a single or broken power-law together with a parametric extinction law is used to model the individual SEDs. We find 10 cases with significant dust, where the derived extinction, AV, ranges from 0.1-1.0 mag. In four of those, the inferred extinction curves are consistent with the SMC curve. The GRB individual extinction curves have a flat RV distribution with an optimal weighted combined value of RV = 2.61 ± 0.08 (for seven broad coverage cases). The `average GRB extinction curve' is similar to, but slightly steeper than the typical SMC, and consistent with the SMC Bar extinction curve at ˜95% confidence level. The resultant steeper extinction curves imply populations of small grains, where large dust grains may be destroyed due to GRB activity. Another possibility could be that young age and/or lower metallicities of GRBs environments are responsible for the steeper curves.

Context-dependent encoding of fear and extinction memories in a large-scale network model of the basal amygdala.

Science.gov (United States)

Vlachos, Ioannis; Herry, Cyril; Lüthi, Andreas; Aertsen, Ad; Kumar, Arvind

2011-03-01

The basal nucleus of the amygdala (BA) is involved in the formation of context-dependent conditioned fear and extinction memories. To understand the underlying neural mechanisms we developed a large-scale neuron network model of the BA, composed of excitatory and inhibitory leaky-integrate-and-fire neurons. Excitatory BA neurons received conditioned stimulus (CS)-related input from the adjacent lateral nucleus (LA) and contextual input from the hippocampus or medial prefrontal cortex (mPFC). We implemented a plasticity mechanism according to which CS and contextual synapses were potentiated if CS and contextual inputs temporally coincided on the afferents of the excitatory neurons. Our simulations revealed a differential recruitment of two distinct subpopulations of BA neurons during conditioning and extinction, mimicking the activation of experimentally observed cell populations. We propose that these two subgroups encode contextual specificity of fear and extinction memories, respectively. Mutual competition between them, mediated by feedback inhibition and driven by contextual inputs, regulates the activity in the central amygdala (CEA) thereby controlling amygdala output and fear behavior. The model makes multiple testable predictions that may advance our understanding of fear and extinction memories.

Context-dependent encoding of fear and extinction memories in a large-scale network model of the basal amygdala.

Directory of Open Access Journals (Sweden)

Ioannis Vlachos

2011-03-01

Full Text Available The basal nucleus of the amygdala (BA is involved in the formation of context-dependent conditioned fear and extinction memories. To understand the underlying neural mechanisms we developed a large-scale neuron network model of the BA, composed of excitatory and inhibitory leaky-integrate-and-fire neurons. Excitatory BA neurons received conditioned stimulus (CS-related input from the adjacent lateral nucleus (LA and contextual input from the hippocampus or medial prefrontal cortex (mPFC. We implemented a plasticity mechanism according to which CS and contextual synapses were potentiated if CS and contextual inputs temporally coincided on the afferents of the excitatory neurons. Our simulations revealed a differential recruitment of two distinct subpopulations of BA neurons during conditioning and extinction, mimicking the activation of experimentally observed cell populations. We propose that these two subgroups encode contextual specificity of fear and extinction memories, respectively. Mutual competition between them, mediated by feedback inhibition and driven by contextual inputs, regulates the activity in the central amygdala (CEA thereby controlling amygdala output and fear behavior. The model makes multiple testable predictions that may advance our understanding of fear and extinction memories.

Two lines of sight with exceedingly anomalous ultraviolet interstellar extinction

International Nuclear Information System (INIS)

Cardelli, J.A.; Savage, B.D.

1988-01-01

Low-resolution IUE data toward HD 62542 reveal an extinction curve with an extremely broad and weak UV extinction bump and the highest FUV extinction yet observed in the Milky Way. Parameters describing the central position and FWHM for weak bumps observed toward HD 62542 and HD 29647 are derived using analytical fitting techniques. In both cases, the bump central positions are shifted shortward of 2175 A with an initial wavelength of 2110 A for HD 62542 and an initial wavelength of 2128 A for HD 29647. The bump FWHM is found to be 1.29/micron and 1.62/micron for HD 62542 and HD 29647, respectively. 75 references

Extinction of planetary nebulae and the turbulent structure of the galaxy

International Nuclear Information System (INIS)

Lerche, I.; Milne, D.K.

1980-01-01

Fluctuations in the extinction of planetary nebulae provide strong support for the concept of a turbulent interstellar medium. We have analyzed theoretically the mean extinction and its variance as a function of height, z, above the galactic plane. The mean increases monotonically, and exponentially, to a saturation level. The variance increases as z 2 for small z and has damped oscillations for intermediate z, before levelling off at large z. The observed mean extinction and the observed variance are found to be in excellent agreement with these theoretical deductions. The spatial scale of the mean extinction is estimated to be 100 pc; the oscillation scale of the variance and the damping scale of the oscillations are estimated to be about 200 +- 100 pc. The rms level of density fluctuations in the absorbing material causing the extinction is about equal to the mean value

Reorganization of Anatomical Connectome following Electroconvulsive Therapy in Major Depressive Disorder

Directory of Open Access Journals (Sweden)

Jinkun Zeng

2015-01-01

Full Text Available Objective. Electroconvulsive therapy (ECT is considered one of the most effective and fast-acting treatment options for depressive episodes. Little is known, however, about ECT’s enabling brain (neuroplasticity effects, particular for plasticity of white matter pathway. Materials and Methods. We collected longitudinal diffusion tensor imaging in the first-episode, drug-naïve major depressive disorder (MDD patients n=24 before and after a predefined time window ECT treatment. We constructed large-scale anatomical networks derived from white matter fiber tractography and evaluated the topological reorganization using graph theoretical analysis. We also assessed the relationship between topological reorganization with improvements in depressive symptoms. Results. Our investigation revealed three main findings: (1 the small-worldness was persistent after ECT series; (2 anatomical connections changes were found in limbic structure, temporal and frontal lobes, in which the connection changes between amygdala and parahippocampus correlate with depressive symptom reduction; (3 significant nodal strength changes were found in right paralimbic network. Conclusions. ECT elicits neuroplastic processes associated with improvements in depressive symptoms that act to specific local ventral frontolimbic circuits, but not small-world property. Overall, ECT induced topological reorganization in large-scale brain structural network, opening up new avenues to better understand the mode of ECT action in MDD.

Artificial light at night confounds broad-scale habitat use by migrating birds

NARCIS (Netherlands)

McLaren, J.D.; Buler, J.J.; Schreckengost, T.; Smolinsky, J.A.; Boone, M.; van Loon, E.E.; Dawson, D.K.; Walters, E.L.

With many of the world's migratory bird populations in alarming decline, broad-scale assessments of responses to migratory hazards may prove crucial to successful conservation efforts. Most birds migrate at night through increasingly light-polluted skies. Bright light sources can attract airborne

Climate change, elevational range shifts, and bird extinctions.

Science.gov (United States)

Sekercioglu, Cagan H; Schneider, Stephen H; Fay, John P; Loarie, Scott R

2008-02-01

Limitations imposed on species ranges by the climatic, ecological, and physiological effects of elevation are important determinants of extinction risk. We modeled the effects of elevational limits on the extinction risk of landbirds, 87% of all bird species. Elevational limitation of range size explained 97% of the variation in the probability of being in a World Conservation Union category of extinction risk. Our model that combined elevational ranges, four Millennium Assessment habitat-loss scenarios, and an intermediate estimate of surface warming of 2.8 degrees C, projected a best guess of 400-550 landbird extinctions, and that approximately 2150 additional species would be at risk of extinction by 2100. For Western Hemisphere landbirds, intermediate extinction estimates based on climate-induced changes in actual distributions ranged from 1.3% (1.1 degrees C warming) to 30.0% (6.4 degrees C warming) of these species. Worldwide, every degree of warming projected a nonlinear increase in bird extinctions of about 100-500 species. Only 21% of the species predicted to become extinct in our scenarios are currently considered threatened with extinction. Different habitat-loss and surface-warming scenarios predicted substantially different futures for landbird species. To improve the precision of climate-induced extinction estimates, there is an urgent need for high-resolution measurements of shifts in the elevational ranges of species. Given the accelerating influence of climate change on species distributions and conservation, using elevational limits in a tested, standardized, and robust manner can improve conservation assessments of terrestrial species and will help identify species that are most vulnerable to global climate change. Our climate-induced extinction estimates are broadly similar to those of bird species at risk from other factors, but these estimates largely involve different sets of species.

A robust nonparametric method for quantifying undetected extinctions.

Science.gov (United States)

Chisholm, Ryan A; Giam, Xingli; Sadanandan, Keren R; Fung, Tak; Rheindt, Frank E

2016-06-01

How many species have gone extinct in modern times before being described by science? To answer this question, and thereby get a full assessment of humanity's impact on biodiversity, statistical methods that quantify undetected extinctions are required. Such methods have been developed recently, but they are limited by their reliance on parametric assumptions; specifically, they assume the pools of extant and undetected species decay exponentially, whereas real detection rates vary temporally with survey effort and real extinction rates vary with the waxing and waning of threatening processes. We devised a new, nonparametric method for estimating undetected extinctions. As inputs, the method requires only the first and last date at which each species in an ensemble was recorded. As outputs, the method provides estimates of the proportion of species that have gone extinct, detected, or undetected and, in the special case where the number of undetected extant species in the present day is assumed close to zero, of the absolute number of undetected extinct species. The main assumption of the method is that the per-species extinction rate is independent of whether a species has been detected or not. We applied the method to the resident native bird fauna of Singapore. Of 195 recorded species, 58 (29.7%) have gone extinct in the last 200 years. Our method projected that an additional 9.6 species (95% CI 3.4, 19.8) have gone extinct without first being recorded, implying a true extinction rate of 33.0% (95% CI 31.0%, 36.2%). We provide R code for implementing our method. Because our method does not depend on strong assumptions, we expect it to be broadly useful for quantifying undetected extinctions. © 2016 Society for Conservation Biology.

Spatiotemporal exploratory models for broad-scale survey data.

Science.gov (United States)

Fink, Daniel; Hochachka, Wesley M; Zuckerberg, Benjamin; Winkler, David W; Shaby, Ben; Munson, M Arthur; Hooker, Giles; Riedewald, Mirek; Sheldon, Daniel; Kelling, Steve

2010-12-01

The distributions of animal populations change and evolve through time. Migratory species exploit different habitats at different times of the year. Biotic and abiotic features that determine where a species lives vary due to natural and anthropogenic factors. This spatiotemporal variation needs to be accounted for in any modeling of species' distributions. In this paper we introduce a semiparametric model that provides a flexible framework for analyzing dynamic patterns of species occurrence and abundance from broad-scale survey data. The spatiotemporal exploratory model (STEM) adds essential spatiotemporal structure to existing techniques for developing species distribution models through a simple parametric structure without requiring a detailed understanding of the underlying dynamic processes. STEMs use a multi-scale strategy to differentiate between local and global-scale spatiotemporal structure. A user-specified species distribution model accounts for spatial and temporal patterning at the local level. These local patterns are then allowed to "scale up" via ensemble averaging to larger scales. This makes STEMs especially well suited for exploring distributional dynamics arising from a variety of processes. Using data from eBird, an online citizen science bird-monitoring project, we demonstrate that monthly changes in distribution of a migratory species, the Tree Swallow (Tachycineta bicolor), can be more accurately described with a STEM than a conventional bagged decision tree model in which spatiotemporal structure has not been imposed. We also demonstrate that there is no loss of model predictive power when a STEM is used to describe a spatiotemporal distribution with very little spatiotemporal variation; the distribution of a nonmigratory species, the Northern Cardinal (Cardinalis cardinalis).

Modelling of local extinction and reignition of the flame

Energy Technology Data Exchange (ETDEWEB)

Brink, A.; Kilpinen, P.; Hupa, M. [Aabo Akademi, Turku (Finland); Kjaeldman, L. [VTT Energy, Espoo (Finland); Jaeaeskelaeinen, K. [Imatran Voima Oy, Helsinki (Finland)

1996-12-31

The influence of the relations between the chemical time scale and the turbulent time scale on local extinction in turbulent flames has been studied. The results from the numerical investigation of a non-swirling flame in a sudden-expansion combustor was compared with measurements and computations reported in the literature. The turbulence-chemistry interaction was modelled using the Eddy-Dissipation Concept (EDC). In the study, different turbulent time scales were used; the Kolmogorov related time scale proposed in the EDC model and two turbulent time scales related to k/{epsilon}. The chemical time scale has been obtained from a model based on calculations with a comprehensive chemical reaction scheme. The results indicate that the Kolmogorov related time scale of the EDC model is too short to be used as an extinction criterium. The two k/{epsilon} related time scales both resulted in a closer agreement between the numerically obtained and the measured results. The result indicates that the time scale used in the EDC model should be further investigated before confident results from modelling of flows with extinction effects can be obtained. (author)

Modelling of local extinction and reignition of the flame

Energy Technology Data Exchange (ETDEWEB)

Brink, A; Kilpinen, P; Hupa, M [Aabo Akademi, Turku (Finland); Kjaeldman, L [VTT Energy, Espoo (Finland); Jaeaeskelaeinen, K [Imatran Voima Oy, Helsinki (Finland)

1997-12-31

The influence of the relations between the chemical time scale and the turbulent time scale on local extinction in turbulent flames has been studied. The results from the numerical investigation of a non-swirling flame in a sudden-expansion combustor was compared with measurements and computations reported in the literature. The turbulence-chemistry interaction was modelled using the Eddy-Dissipation Concept (EDC). In the study, different turbulent time scales were used; the Kolmogorov related time scale proposed in the EDC model and two turbulent time scales related to k/{epsilon}. The chemical time scale has been obtained from a model based on calculations with a comprehensive chemical reaction scheme. The results indicate that the Kolmogorov related time scale of the EDC model is too short to be used as an extinction criterium. The two k/{epsilon} related time scales both resulted in a closer agreement between the numerically obtained and the measured results. The result indicates that the time scale used in the EDC model should be further investigated before confident results from modelling of flows with extinction effects can be obtained. (author)

Emergent reorganization of an evolving experimental landscape under changing climatic forcing

Science.gov (United States)

Singh, A.; Tejedor, A.; Zaliapin, I. V.; Reinhardt, L.; Foufoula-Georgiou, E.

2014-12-01

Understanding landscape re-organization under changing climatic forcing is fundamental to advancing our understanding of geomorphic transport laws under transient conditions, developing predictive models of landscape response to external perturbations, and interpreting the stratigraphic record for past climates by incorporating possible regime shifts. Real landscape observations for long-term analysis are limited and to this end a high resolution controlled laboratory experiment was conducted at the St. Anthony Falls laboratory at the University of Minnesota. Elevation data were collected at temporal resolution of 5 mins and spatial resolution of 0.5 mm as the landscape approached steady state (for a constant uplift and precipitation rate) and in the transient state (under the same uplift and 5x precipitation). The results reveal rapid topographic re-organization under a five-fold precipitation increase with the fluvial regime expanding into previously debris dominated regime, accelerated erosion happening at hillslope scales, and rivers shifting from an erosion-limited to a transport-limited regime. By studying the space-time structure of the individual erosional and depositional events in terms of their size, location, clustering, and total volume we report complex space-time patterns of change which are scale-dependent and bounded by the river network topology. At the same time, the river network topology itself adjusts at smaller scales, with new channels added to accommodate increased hillslope erosional transport, further adjusting the landscape. Some new ideas related to landscape variability and entropy evolution at different scales during steady and transient states and the possibility of analyzing the self-organization with Optimal Mass Transport (OMT) metrics to infer possible underlying "optimality" principles governing the re-organization will also be presented.

Food plant diversity as broad-Scale Determinant of Avian Frugivore Richness

DEFF Research Database (Denmark)

Kissling, W. Daniel; Rahbek, Carsten; Böhning-Gaese, Katrin

2007-01-01

from niche assembly mechanisms (e.g. coevolutionary adaptations to fruit size, fruit colour or vertical stratification of fruit presentation) or, alternatively, from stochastic speciation-extinction processes. In any case, the close relationship between species richness of Ficus and avian frugivores......The causes of variation in animal species richness at large spatial scales are intensively debated. Here, we examine whether the diversity of food plants, contemporary climate and energy, or habitat heterogeneity determine species richness patterns of avian frugivores across sub-Saharan Africa....... Path models indicate that species richness of Ficus (their fruits being one of the major food resources for frugivores in the tropics) has the strongest direct effect on richness of avian frugivores, whereas the influences of variables related to water-energy and habitat heterogeneity are mainly...

Assessment of nuclear data needs for broad-group SCALE library related to WWER spent fuel applications

International Nuclear Information System (INIS)

Zalesky, K.; Markova, L.

1999-12-01

A preliminary study aimed at the issue of feasibility to generate a broad-group SCALE library related to WWER spent fuel applications was made. The SCALE code system has been installed and is being used in many countries operating WWER-type reactors for criticality and shielding analyses as well as spent fuel isotopic inventory calculations but still without an extensive validation and verification for the WWER environment. This study should be a contribution to QA connected with the SCALE code system application for the WWER calculations as a basis on which the generation of the specific WWER SCALE library can be prepared. Possible ways of the broad-group library development are described. (author)

Perceiving beauty in all women: Psychometric evaluation of the Broad Conceptualization of Beauty Scale.

Science.gov (United States)

Tylka, Tracy L; Iannantuono, Amy C

2016-06-01

Women's ability to broadly conceptualize beauty (i.e., perceive many looks, appearances, body sizes/shapes, and inner characteristics as beautiful) has been identified as a facet of positive body image in qualitative research. A scale is needed to be able to assess this construct within quantitative research. Therefore, we developed the Broad Conceptualization of Beauty Scale (BCBS), which measures the extent women define female beauty widely within external and internal characteristics, and examined its psychometric properties among four community samples totaling 1086 women. Exploratory and confirmatory factor analyses revealed a unidimensional structure with nine items. The internal consistency, test-retest reliability, and construct (convergent, discriminant, and incremental) validity of its scores were upheld. Researchers and clinicians can use the BCBS alone to assess women's perceptions of female beauty, or they can use the BCBS alongside women's perceptions of self-beauty to more comprehensively explore women's ability to broadly conceptualize beauty for others and themselves. Copyright © 2016 Elsevier Ltd. All rights reserved.

High speed ultra-broadband amplitude modulators with ultrahigh extinction >65 dB.

Science.gov (United States)

Liu, S; Cai, H; DeRose, C T; Davids, P; Pomerene, A; Starbuck, A L; Trotter, D C; Camacho, R; Urayama, J; Lentine, A

2017-05-15

We experimentally demonstrate ultrahigh extinction ratio (>65 dB) amplitude modulators (AMs) that can be electrically tuned to operate across a broad spectral range of 160 nm from 1480 - 1640 nm and 95 nm from 1280 - 1375 nm. Our on-chip AMs employ one extra coupler compared with conventional Mach-Zehnder interferometers (MZI), thus form a cascaded MZI (CMZI) structure. Either directional or adiabatic couplers are used to compose the CMZI AMs and experimental comparisons are made between these two different structures. We investigate the performance of CMZI AMs under extreme conditions such as using 95:5 split ratio couplers and unbalanced waveguide losses. Electro-optic phase shifters are also integrated in the CMZI AMs for high-speed operation. Finally, we investigate the output optical phase when the amplitude is modulated, which provides us valuable information when both amplitude and phase are to be controlled. Our demonstration not only paves the road to applications such as quantum information processing that requires high extinction ratio AMs but also significantly alleviates the tight fabrication tolerance needed for large-scale integrated photonics.

Climate change not to blame for late Quaternary megafauna extinctions in Australia.

Science.gov (United States)

Saltré, Frédérik; Rodríguez-Rey, Marta; Brook, Barry W; Johnson, Christopher N; Turney, Chris S M; Alroy, John; Cooper, Alan; Beeton, Nicholas; Bird, Michael I; Fordham, Damien A; Gillespie, Richard; Herrando-Pérez, Salvador; Jacobs, Zenobia; Miller, Gifford H; Nogués-Bravo, David; Prideaux, Gavin J; Roberts, Richard G; Bradshaw, Corey J A

2016-01-29

Late Quaternary megafauna extinctions impoverished mammalian diversity worldwide. The causes of these extinctions in Australia are most controversial but essential to resolve, because this continent-wide event presaged similar losses that occurred thousands of years later on other continents. Here we apply a rigorous metadata analysis and new ensemble-hindcasting approach to 659 Australian megafauna fossil ages. When coupled with analysis of several high-resolution climate records, we show that megafaunal extinctions were broadly synchronous among genera and independent of climate aridity and variability in Australia over the last 120,000 years. Our results reject climate change as the primary driver of megafauna extinctions in the world's most controversial context, and instead estimate that the megafauna disappeared Australia-wide ∼13,500 years after human arrival, with shorter periods of coexistence in some regions. This is the first comprehensive approach to incorporate uncertainty in fossil ages, extinction timing and climatology, to quantify mechanisms of prehistorical extinctions.

Climate change not to blame for late Quaternary megafauna extinctions in Australia

Science.gov (United States)

Saltré, Frédérik; Rodríguez-Rey, Marta; Brook, Barry W.; Johnson, Christopher N; Turney, Chris S. M.; Alroy, John; Cooper, Alan; Beeton, Nicholas; Bird, Michael I.; Fordham, Damien A.; Gillespie, Richard; Herrando-Pérez, Salvador; Jacobs, Zenobia; Miller, Gifford H.; Nogués-Bravo, David; Prideaux, Gavin J.; Roberts, Richard G.; Bradshaw, Corey J. A.

2016-01-01

Late Quaternary megafauna extinctions impoverished mammalian diversity worldwide. The causes of these extinctions in Australia are most controversial but essential to resolve, because this continent-wide event presaged similar losses that occurred thousands of years later on other continents. Here we apply a rigorous metadata analysis and new ensemble-hindcasting approach to 659 Australian megafauna fossil ages. When coupled with analysis of several high-resolution climate records, we show that megafaunal extinctions were broadly synchronous among genera and independent of climate aridity and variability in Australia over the last 120,000 years. Our results reject climate change as the primary driver of megafauna extinctions in the world's most controversial context, and instead estimate that the megafauna disappeared Australia-wide ∼13,500 years after human arrival, with shorter periods of coexistence in some regions. This is the first comprehensive approach to incorporate uncertainty in fossil ages, extinction timing and climatology, to quantify mechanisms of prehistorical extinctions. PMID:26821754

Anisotropic extinction distortion of the galaxy correlation function

International Nuclear Information System (INIS)

Fang Wenjuan; Hui Lam; Menard, Brice; May, Morgan; Scranton, Ryan

2011-01-01

Similar to the magnification of the galaxies' fluxes by gravitational lensing, the extinction of the fluxes by comic dust, whose existence is recently detected by [B. Menard, R. Scranton, M. Fukugita, and G. Richards, Mon. Not. R. Astron. Soc. 405, 1025 (2010).], also modifies the distribution of a flux-selected galaxy sample. We study the anisotropic distortion by dust extinction to the 3D galaxy correlation function, including magnification bias and redshift distortion at the same time. We find the extinction distortion is most significant along the line of sight and at large separations, similar to that by magnification bias. The correction from dust extinction is negative except at sufficiently large transverse separations, which is almost always opposite to that from magnification bias (we consider a number count slope s>0.4). Hence, the distortions from these two effects tend to reduce each other. At low z (< or approx. 1), the distortion by extinction is stronger than that by magnification bias, but at high z, the reverse holds. We also study how dust extinction affects probes in real space of the baryon acoustic oscillations (BAO) and the linear redshift distortion parameter β. We find its effect on BAO is negligible. However, it introduces a positive scale-dependent correction to β that can be as large as a few percent. At the same time, we also find a negative scale-dependent correction from magnification bias, which is up to percent level at low z, but to ∼40% at high z. These corrections are non-negligible for precision cosmology, and should be considered when testing General Relativity through the scale-dependence of β.

Interbunch extinction measurement at the BNL AGS for the KOPIO experiment

Energy Technology Data Exchange (ETDEWEB)

Ahrens, L. [Brookhaven National Laboratory (United States); Artamonov, A. [Institute for High Energy Physics, Protvino (Russian Federation); Atoian, G. [Yale University (United States); Brown, K. [Brookhaven National Laboratory (United States); Cantley, C. [Brookhaven National Laboratory (United States); Cartiglia, N. [Stony Brook University (United States); Christidi, I.A. [Stony Brook University (United States); Glenn, J.W. [Brookhaven National Laboratory (United States); Hatzikoutelis, A. [Virginia Polytechnic Institute and State Universtiy (United States)]. E-mail: athans@phys.vt.edu; Jaffe, D.E. [Brookhaven National Laboratory (United States); Koscielniak, S. [TRIUMF (Canada); Lazarus, D.M. [Brookhaven National Laboratory (United States); Mabanta, J. [Brookhaven National Laboratory (United States); Marx, M. [Stony Brook University (United States); Pile, P. [Brookhaven National Laboratory (United States); Redlinger, G. [Brookhaven National Laboratory (United States); Scarlett, C. [Brookhaven National Laboratory (United States); Sivertz, M. [Brookhaven National Laboratory (United States)

2006-05-10

The KOPIO experiment at the BNL AGS required an extracted proton beam in which a debunched, coasting beam is forced between empty longitudinal RF buckets to form microbunches. The goal of the measurement described here was to obtain a low background determination of the fraction of protons coming from the AGS slowly extracted beam at times between microbunches (interbunch extinction). The effect on interbunch extinction of variations in the RF cavity voltage, the momentum dispersion of the beam and the main guide field voltage-ripple was studied. It was found that there exists a broad range of operating parameters that could allow the AGS to produce microbunches with the interbunch extinction better than the KOPIO experiment requirement. Results obtained in this study gave interbunch extinctions better than 10{sup -5} (1%) of KOPIO's upper limit.

AESoP: Astronomical Extinction Spectrophotometer

Science.gov (United States)

Linford, Justin; McGraw, J.; Zimmer, P.; Ackermann, M.; Fitch, J.

2009-01-01

The Earth's atmosphere is a major obstruction to the precision and accuracy of ground-based photometry. The atmosphere removes light from astronomical objects both by absorption and scattering by constituent molecules, aerosols and clouds. These effects can change significantly over short time periods and over modest angles on the sky. To further understand these effects, the UNM Measurement Astrophysics Group has designed, built and recently deployed the Astronomical Extinction Spectrophotometer (AESoP), a 100mm objective grating spectrometer. By monitoring bright stars in sensibly the same direction as a larger photometric telescope is observing, AESoP will measure the wavelength-dependent extinction due to the Earth's atmosphere from 450nm to 900nm on time scales of approximately one minute. The collocated Astronomical LIDAR for Extinction (ALE) provides a high-precision monochromatic extinction measurement at 527nm. Knowing the extinction at a single wavelength allows us to pin the relative spectra generated by AESoP. These extinction spectra can then be integrated over the bandpass of the photometric telescope system to create real time corrections of observations. We present the design and construction of AESoP along with the preliminary results of our first combined observing campaign. This effort is our first step toward breaking the 1% photometry barrier. This project is funded by AFRL Grant FA9451-04-2-0355

Co-Plaintigff in Judicial Reorganization

Directory of Open Access Journals (Sweden)

Liliane Gonçalves Matos

2016-12-01

Full Text Available The aim of the study it was to analyze the possibility of the economic group file a single request for judicial reorganization. Concerning the methodology, the study is a descriptive - analytic research, analyzing the legal doctrines and jurisprudence about the subject. It has been shown that the reorganization of groups, instead of separated companies may result benefits, as a company of the group can help to recover the others that are facing difficulties, but there is the possibility to create a negative incentive for the development of global business activity. It was concluded that the active joinder in bankruptcy is feasible, but it would be more prudent for each group company present its own reorganization  plan.

Complete reorganization of the motor cortex of adult rats following long-term spinal cord injuries.

Science.gov (United States)

Tandon, Shashank; Kambi, Niranjan; Mohammed, Hisham; Jain, Neeraj

2013-07-01

Understanding brain reorganization following long-term spinal cord injuries is important for optimizing recoveries based on residual function as well as developing brain-controlled assistive devices. Although it has been shown that the motor cortex undergoes partial reorganization within a few weeks after peripheral and spinal cord injuries, it is not known if the motor cortex of rats is capable of large-scale reorganization after longer recovery periods. Here we determined the organization of the rat (Rattus norvegicus) motor cortex at 5 or more months after chronic lesions of the spinal cord at cervical levels using intracortical microstimulation. The results show that, in the rats with the lesions, stimulation of neurons in the de-efferented forelimb motor cortex no longer evokes movements of the forelimb. Instead, movements of the body parts in the adjacent representations, namely the whiskers and neck were evoked. In addition, at many sites, movements of the ipsilateral forelimb were observed at threshold currents. The extent of representations of the eye, jaw and tongue movements was unaltered by the lesion. Thus, large-scale reorganization of the motor cortex leads to complete filling-in of the de-efferented cortex by neighboring representations following long-term partial spinal cord injuries at cervical levels in adult rats. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Hierarchical reorganization of dimensions in OLAP visualizations.

Science.gov (United States)

Lafon, Sébastien; Bouali, Fatma; Guinot, Christiane; Venturini, Gilles

2013-11-01

In this paper, we propose a new method for the visual reorganization of online analytical processing (OLAP) cubes that aims at improving their visualization. Our method addresses dimensions with hierarchically organized members. It uses a genetic algorithm that reorganizes k-ary trees. Genetic operators perform permutations of subtrees to optimize a visual homogeneity function. We propose several ways to reorganize an OLAP cube depending on which set of members is selected for the reorganization: all of the members, only the displayed members, or the members at a given level (level by level approach). The results that are evaluated by using optimization criteria show that our algorithm has a reliable performance even when it is limited to 1 minute runs. Our algorithm was integrated in an interactive 3D interface for OLAP. A user study was conducted to evaluate our approach with users. The results highlight the usefulness of reorganization in two OLAP tasks.

Area-based assessment of extinction risk.

Science.gov (United States)

Hei, Fangliang

2012-05-01

Underpinning the International Union for Conservation of Nature (IUCN) Red List is the assessment of extinction risk as determined by the size and degree of loss of populations. The IUCN system lists a species as Critically Endangered, Endangered, or Vulnerable if its population size declines 80%, 50%, or 30% within a given time frame. However, effective implementation of the system faces substantial challenges and uncertainty because geographic scale data on population size and long-term dynamics are scarce. I develop a model to quantify extinction risk using a measure based on a species' distribution, a much more readily obtained quantity. The model calculates the loss of the area of occupancy that is equivalent to the loss of a given proportion of a population. It is a very simple yet general model that has no free parameters and is independent of scale. The model predicted well the distributions of 302 tree species at a local scale and the distributions of 348 species of North American land birds. This area-based model provides a solution to the long-standing problem for IUCN assessments of lack of data on population sizes, and thus it will contribute to facilitating the quantification of extinction risk worldwide.

Spatially Synchronous Extinction of Species under External Forcing

Science.gov (United States)

Amritkar, R. E.; Rangarajan, Govindan

2006-06-01

More than 99% of the species that ever existed on the surface of the Earth are now extinct and their extinction on a global scale has been a puzzle. One may think that a species under an external threat may survive in some isolated locations leading to the revival of the species. Using a general model we show that, under a common external forcing, the species with a quadratic saturation term first undergoes spatial synchronization and then extinction. The effect can be observed even when the external forcing acts only on some locations provided the dynamics contains a synchronizing term. Absence of the quadratic saturation term can help the species to avoid extinction.

Unbounded autocatalytic growth on diffusive substrate: The extinction transition

International Nuclear Information System (INIS)

Moalem, Sasi; Shnerb, Nadav M.

2007-01-01

The effect of diffusively correlated spatial fluctuations on the proliferation-extinction transition of autocatalytic agents is investigated numerically. Reactants adaptation to spatio-temporal active regions is shown to lead to proliferation even if the mean field rate equations predict extinction, in agreement with previous theoretical predictions. While in the proliferation phase the system admits a typical time scale that dictates the exponential growth, the extinction times distribution obeys a power law at the parameter region considered

Performance Evaluation of CRW Reef-Scale and Broad-Scale SST-Based Coral Monitoring Products in Fringing Reef Systems of Tobago

Directory of Open Access Journals (Sweden)

Shaazia S. Mohammed

2015-12-01

Full Text Available Satellite-derived sea surface temperature (SST is used to monitor coral bleaching through the National Oceanic and Atmospheric Administration’s Coral Reef Watch (CRW Decision Support System (DSS. Since 2000, a broad-scale 50 km SST was used to monitor thermal stress for coral reefs globally. However, some discrepancies were noted when applied to small-scale fringing coral reefs. To address this, CRW created a new DSS, specifically targeted at or near reef scales. Here, we evaluated the new reef-scale (5 km resolution products using in situ temperature data and coral bleaching surveys which were also compared with the heritage broad-scale (50 km for three reefs (Buccoo Reef, Culloden and Speyside of the southern Caribbean island of Tobago. Seasonal and annual biases indicated the new 5 km SST generally represents the conditions at these reefs more accurately and more consistently than the 50 km SST. Consistency between satellite and in situ temperature data influences the performance of anomaly-based predictions of bleaching: the 5 km DHW product showed better consistency with bleaching observations than the 50 km product. These results are the first to demonstrate the improvement of the 5 km products over the 50 km predecessors and support their use in monitoring thermal stress of reefs in the southern Caribbean.

Precision Photometric Extinction Corrections from Direct Atmospheric Measurements

Science.gov (United States)

McGraw, John T.; Zimmer, P.; Linford, J.; Simon, T.; Measurement Astrophysics Research Group

2009-01-01

For decades astronomical extinction corrections have been accomplished using nightly mean extinction coefficients derived from Langley plots measured with the same telescope used for photometry. Because this technique results in lost time on program fields, observers only grudgingly made sporadic extinction measurements. Occasionally extinction corrections are not measured nightly but are made using tabulated mean monthly or even quarterly extinction coefficients. Any observer of the sky knows that Earth's atmosphere is an ever-changing fluid in which is embedded extinction sources ranging from Rayleigh (molecular) scattering to aerosol, smoke and dust scattering and absorption, to "just plain cloudy.” Our eyes also tell us that the type, direction and degree of extinction changes on time scales of minutes or less - typically shorter than many astronomical observations. Thus, we should expect that atmospheric extinction can change significantly during a single observation. Mean extinction coefficients might be well-defined nightly means, but those means have high variance because they do not accurately record the wavelength-, time-, and angle-dependent extinction actually affecting each observation. Our research group is implementing lidar measurements made in the direction of observation with one minute cadence, from which the absolute monochromatic extinction can be measured. Simultaneous spectrophotometry of nearby bright standard stars allows derivation and MODTRAN modeling atmospheric transmission as a function of wavelength for the atmosphere through which an observation is made. Application of this technique is demonstrated. Accurate real-time extinction measurements are an enabling factor for sub-1% photometry. This research is supported by NSF Grant 0421087 and AFRL Grant #FA9451-04-2-0355.

ON GALACTIC DENSITY MODELING IN THE PRESENCE OF DUST EXTINCTION

International Nuclear Information System (INIS)

Bovy, Jo; Rix, Hans-Walter; Schlafly, Edward F.; Green, Gregory M.; Finkbeiner, Douglas P.

2016-01-01

Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant small-scale structure in the three-dimensional interstellar dust extinction. We introduce a novel framework for analyzing the importance of small-scale structure in the extinction. This formalism demonstrates that the spatially complex effect of extinction on the selection function of a pencil-beam or contiguous sky survey is equivalent to a low-pass filtering of the extinction-affected selection function with the smooth density field. We find that the angular resolution of current 3D extinction maps is sufficient for analyzing Gaia sub-samples of millions of stars. However, the current distance resolution is inadequate and needs to be improved by an order of magnitude, especially in the inner Galaxy. We also present a practical and efficient method for properly taking the effect of extinction into account in analyses of Galactic structure through an effective selection function. We illustrate its use with the selection function of red-clump stars in APOGEE using and comparing a variety of current 3D extinction maps

ON GALACTIC DENSITY MODELING IN THE PRESENCE OF DUST EXTINCTION

Energy Technology Data Exchange (ETDEWEB)

Bovy, Jo [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, M5S 3H4 (Canada); Rix, Hans-Walter; Schlafly, Edward F. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Green, Gregory M.; Finkbeiner, Douglas P., E-mail: bovy@astro.utoronto.ca [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-02-20

Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant small-scale structure in the three-dimensional interstellar dust extinction. We introduce a novel framework for analyzing the importance of small-scale structure in the extinction. This formalism demonstrates that the spatially complex effect of extinction on the selection function of a pencil-beam or contiguous sky survey is equivalent to a low-pass filtering of the extinction-affected selection function with the smooth density field. We find that the angular resolution of current 3D extinction maps is sufficient for analyzing Gaia sub-samples of millions of stars. However, the current distance resolution is inadequate and needs to be improved by an order of magnitude, especially in the inner Galaxy. We also present a practical and efficient method for properly taking the effect of extinction into account in analyses of Galactic structure through an effective selection function. We illustrate its use with the selection function of red-clump stars in APOGEE using and comparing a variety of current 3D extinction maps.

Estimating extinction using unsupervised machine learning

Science.gov (United States)

Meingast, Stefan; Lombardi, Marco; Alves, João

2017-05-01

Dust extinction is the most robust tracer of the gas distribution in the interstellar medium, but measuring extinction is limited by the systematic uncertainties involved in estimating the intrinsic colors to background stars. In this paper we present a new technique, Pnicer, that estimates intrinsic colors and extinction for individual stars using unsupervised machine learning algorithms. This new method aims to be free from any priors with respect to the column density and intrinsic color distribution. It is applicable to any combination of parameters and works in arbitrary numbers of dimensions. Furthermore, it is not restricted to color space. Extinction toward single sources is determined by fitting Gaussian mixture models along the extinction vector to (extinction-free) control field observations. In this way it becomes possible to describe the extinction for observed sources with probability densities, rather than a single value. Pnicer effectively eliminates known biases found in similar methods and outperforms them in cases of deep observational data where the number of background galaxies is significant, or when a large number of parameters is used to break degeneracies in the intrinsic color distributions. This new method remains computationally competitive, making it possible to correctly de-redden millions of sources within a matter of seconds. With the ever-increasing number of large-scale high-sensitivity imaging surveys, Pnicer offers a fast and reliable way to efficiently calculate extinction for arbitrary parameter combinations without prior information on source characteristics. The Pnicer software package also offers access to the well-established Nicer technique in a simple unified interface and is capable of building extinction maps including the Nicest correction for cloud substructure. Pnicer is offered to the community as an open-source software solution and is entirely written in Python.

Task-specific reorganization of the auditory cortex in deaf humans.

Science.gov (United States)

Bola, Łukasz; Zimmermann, Maria; Mostowski, Piotr; Jednoróg, Katarzyna; Marchewka, Artur; Rutkowski, Paweł; Szwed, Marcin

2017-01-24

The principles that guide large-scale cortical reorganization remain unclear. In the blind, several visual regions preserve their task specificity; ventral visual areas, for example, become engaged in auditory and tactile object-recognition tasks. It remains open whether task-specific reorganization is unique to the visual cortex or, alternatively, whether this kind of plasticity is a general principle applying to other cortical areas. Auditory areas can become recruited for visual and tactile input in the deaf. Although nonhuman data suggest that this reorganization might be task specific, human evidence has been lacking. Here we enrolled 15 deaf and 15 hearing adults into an functional MRI experiment during which they discriminated between temporally complex sequences of stimuli (rhythms). Both deaf and hearing subjects performed the task visually, in the central visual field. In addition, hearing subjects performed the same task in the auditory modality. We found that the visual task robustly activated the auditory cortex in deaf subjects, peaking in the posterior-lateral part of high-level auditory areas. This activation pattern was strikingly similar to the pattern found in hearing subjects performing the auditory version of the task. Although performing the visual task in deaf subjects induced an increase in functional connectivity between the auditory cortex and the dorsal visual cortex, no such effect was found in hearing subjects. We conclude that in deaf humans the high-level auditory cortex switches its input modality from sound to vision but preserves its task-specific activation pattern independent of input modality. Task-specific reorganization thus might be a general principle that guides cortical plasticity in the brain.

Broad-Scale Environmental Conditions Responsible for Post-Fire Vegetation Dynamics

Directory of Open Access Journals (Sweden)

Stuart E. Marsh

2010-11-01

Full Text Available Ecosystem response to disturbance is influenced by environmental conditions at a number of scales. Changes in climate have altered fire regimes across the western United States, and have also likely altered spatio-temporal patterns of post-fire vegetation regeneration. Fire occurrence data and a vegetation index (NDVI derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR were used to monitor post-fire vegetation from 1989 to 2007. We first investigated differences in post-fire rates of vegetation regeneration between ecoregions. We then related precipitation, temperature, and elevation records at four temporal scales to rates of post-fire vegetation regeneration to ascertain the influence of climate on post-fire vegetation dynamics. We found that broad-scale climate factors are an important influence on post-fire vegetation regeneration. Most notably, higher rates of post-fire regeneration occurred with warmer minimum temperatures. Increases in precipitation also resulted in higher rates of post-fire vegetation growth. While explanatory power was slight, multiple statistical approaches provided evidence for real ecological drivers of post-fire regeneration that should be investigated further at finer scales. The sensitivity of post-disturbance vegetation dynamics to climatic drivers has important ramifications for the management of ecosystems under changing climatic conditions. Shifts in temperature and precipitation regimes are likely to result in changes in post-disturbance dynamics, which could represent important feedbacks into the global climate system.

Firm Reorganization : Social Control or Social Contract?

NARCIS (Netherlands)

Aalbers, Hendrik Leendert; Dolfsma, Wilfred; Blinde-Leerentveld, Rowan

Firm reorganizations deeply affect employees. Management can reorganize in different ways, focusing on costs or acknowledging the involvement of employees. The latter implies following a social contract that complements incomplete (formal) labor contracts. Little is known about how the way in which

Probabilistic measures of persistence and extinction in measles (meta)populations.

Science.gov (United States)

Gunning, Christian E; Wearing, Helen J

2013-08-01

Persistence and extinction are fundamental processes in ecological systems that are difficult to accurately measure due to stochasticity and incomplete observation. Moreover, these processes operate on multiple scales, from individual populations to metapopulations. Here, we examine an extensive new data set of measles case reports and associated demographics in pre-vaccine era US cities, alongside a classic England & Wales data set. We first infer the per-population quasi-continuous distribution of log incidence. We then use stochastic, spatially implicit metapopulation models to explore the frequency of rescue events and apparent extinctions. We show that, unlike critical community size, the inferred distributions account for observational processes, allowing direct comparisons between metapopulations. The inferred distributions scale with population size. We use these scalings to estimate extinction boundary probabilities. We compare these predictions with measurements in individual populations and random aggregates of populations, highlighting the importance of medium-sized populations in metapopulation persistence. © 2013 John Wiley & Sons Ltd/CNRS.

A drastic reorganization of industry in the world.What is the driving force

Directory of Open Access Journals (Sweden)

Shinji Naruo

2010-05-01

Full Text Available The purpose of this paper is to show the method and model to analyze the driving force to reorganize the industry. Due to the global economy, many large scale M&A and affiliations are happening in the world. The business alliance and integration are happening in the advanced countries, the transition countries, and the developing countries. There are some factors to impact the reorganization of industry. One is government policy. Another is the market economy. The government has the industrial policy. It guides and leads the industrial structure of the country. Advanced countries had experienced the advancement of industrial structure. On the process of industrial structure advancement, the country improved national income (GNP. Through the process, the enterprise in the industry had experienced integration and separation in the industry. The theory of industrial structure supports the framework of this approach.On the other hand, the market economy also had influenced to the reorganization of industry. Business cycle, competition, and innovation had influenced the reorganization of industry. In capitalism, the shareholder of the company pushes the company to maximize the profit. The shareholder’s pressure could influence the decision of M&A.The theory of industrial organization supports the framework of this approach.The enterprise is in the business environment. Top management of the company is responsible to make a decision to merge or acquire the company. However, the decision is affected by other factors out of business environment. The shareholder influenced the individual enterprise decision. The government policy influenced the industrial structure. This could impose the enterprise to accept the amalgamation in the industry.Both of two influence the reorganization of industry.

NEBULAR AND STELLAR DUST EXTINCTION ACROSS THE DISK OF EMISSION-LINE GALAXIES ON KILOPARSEC SCALES

Energy Technology Data Exchange (ETDEWEB)

Hemmati, Shoubaneh; Mobasher, Bahram; Darvish, Behnam [University of California, Riverside, CA 92512 (United States); Nayyeri, Hooshang; Miller, Sarah [University of California, Irvine, CA 92697 (United States); Sobral, David, E-mail: shemm001@ucr.edu [Universidade de Lisboa, PT1349-018 Lisbon (Portugal)

2015-11-20

We investigate the resolved kiloparsec-scale stellar and nebular dust distribution in eight star-forming galaxies at z ∼ 0.4 in the Great Observatories Origins Deep Survey fields. This is to get a better understanding of the effect of dust attenuation on measurements of physical properties and its variation with redshift. Constructing the observed spectral energy distributions (SEDs) per pixel, based on seven bands of photometric data from Hubble Space Telescope/Advanced Camera for Surveys and WFC3, we performed pixel-by-pixel SED fits to population synthesis models and estimated the small-scale distribution of stellar dust extinction. We use Hα/Hβ nebular emission line ratios from Keck/DEIMOS high-resolution spectra at each spatial resolution element to measure the amount of attenuation faced by ionized gas at different radii from the centers of galaxies. We find a good agreement between the integrated and median of resolved color excess measurements in our galaxies. The ratio of integrated nebular to stellar dust extinction is always greater than unity, but does not show any trend with stellar mass or star formation rate (SFR). We find that inclination plays an important role in the variation of the nebular to stellar excess ratio. The stellar color excess profiles are found to have higher values at the center compared to outer parts of the disk. However, for lower mass galaxies, a similar trend is not found for the nebular color excess. We find that the nebular color excess increases with stellar mass surface density. This explains the absence of radial trend in the nebular color excess in lower mass galaxies which lack a large radial variation of stellar mass surface density. Using standard conversions of SFR surface density to gas mass surface density, and the relation between dust mass surface density and color excess, we find no significant variation in the dust-to-gas ratio in regions with high gas mass surface densities over the scales probed in this

Temporal Dynamics of Recovery from Extinction Shortly after Extinction Acquisition

Science.gov (United States)

Archbold, Georgina E.; Dobbek, Nick; Nader, Karim

2013-01-01

Evidence suggests that extinction is new learning. Memory acquisition involves both short-term memory (STM) and long-term memory (LTM) components; however, few studies have examined early phases of extinction retention. Retention of auditory fear extinction was examined at various time points. Shortly (1-4 h) after extinction acquisition…

Prolonged reorganization of thiol-capped Au nanoparticles layered structures

Directory of Open Access Journals (Sweden)

Sarathi Kundu

2013-09-01

Full Text Available Prolonged reorganization behaviour of mono-, di-, tri- and multi-layer films of Au nanoparticles prepared by Langmuir-Blodgett method on hydrophobic Si(001 substrates have been studied by using X-ray scattering techniques. Out-of-plane study shows that although at the initial stage the reorganization occurs through the compaction of the films keeping the layered structure unchanged but finally all layered structures modify to monolayer structure. Due to this reorganization the Au density increases within the nanometer thick films. In-plane study shows that inside the reorganized films Au nanoparticles are distributed randomly and the particle size modifies as the metallic core of Au nanoparticles coalesces.

Wavelength dependent measurement of extinction in an extended-face crystal of zinc selenide

International Nuclear Information System (INIS)

Stevenson, A.W.; Barnea, Z.

1982-01-01

The effect of extinction on Bijvoet ratios is demonstrated. It is suggested that an observed anomaly in the wavelength dependence of ZnSe Bijvoet ratios is due to the Borrmann effect. It is shown that wavelength dependent studies of extinction may be used to obtain extinction parameters from relative intensity measurements without resorting to a refined scale factor

Analyzing extreme sea levels for broad-scale impact and adaptation studies

Science.gov (United States)

Wahl, T.; Haigh, I. D.; Nicholls, R. J.; Arns, A.; Dangendorf, S.; Hinkel, J.; Slangen, A.

2017-12-01

Coastal impact and adaptation assessments require detailed knowledge on extreme sea levels (ESL), because increasing damage due to extreme events is one of the major consequences of sea-level rise (SLR) and climate change. Over the last few decades, substantial research efforts have been directed towards improved understanding of past and future SLR; different scenarios were developed with process-based or semi-empirical models and used for coastal impact studies at various temporal and spatial scales to guide coastal management and adaptation efforts. Uncertainties in future SLR are typically accounted for by analyzing the impacts associated with a range of scenarios and model ensembles. ESL distributions are then displaced vertically according to the SLR scenarios under the inherent assumption that we have perfect knowledge on the statistics of extremes. However, there is still a limited understanding of present-day ESL which is largely ignored in most impact and adaptation analyses. The two key uncertainties stem from: (1) numerical models that are used to generate long time series of storm surge water levels, and (2) statistical models used for determining present-day ESL exceedance probabilities. There is no universally accepted approach to obtain such values for broad-scale flood risk assessments and while substantial research has explored SLR uncertainties, we quantify, for the first time globally, key uncertainties in ESL estimates. We find that contemporary ESL uncertainties exceed those from SLR projections and, assuming that we meet the Paris agreement, the projected SLR itself by the end of the century. Our results highlight the necessity to further improve our understanding of uncertainties in ESL estimates through (1) continued improvement of numerical and statistical models to simulate and analyze coastal water levels and (2) exploit the rich observational database and continue data archeology to obtain longer time series and remove model bias

Review of broad-scale drought monitoring of forests: Toward an integrated data mining approach

Science.gov (United States)

Steve Norman; Frank H. Koch; William W. Hargrove

2016-01-01

Efforts to monitor the broad-scale impacts of drought on forests often come up short. Drought is a direct stressor of forests as well as a driver of secondary disturbance agents, making a full accounting of drought impacts challenging. General impacts  can be inferred from moisture deficits quantified using precipitation and temperature measurements. However,...

Rethinking Extinction

Science.gov (United States)

Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

2015-01-01

Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavioral technique, and consider whether traditional understandings warrant a re-examination. We discuss the neurobiology, cognitive factors, and major computational theories, and revisit the predominant view that extinction results in new learning that interferes with expression of the original memory. Additionally, we reconsider the limitations of extinction as a technique to prevent the relapse of maladaptive behavior, and discuss novel approaches, informed by contemporary theoretical advances, that augment traditional extinction methods to target and potentially alter maladaptive memories. PMID:26447572

The PHD Domain of Np95 (mUHRF1) Is Involved in Large-Scale Reorganization of Pericentromeric Heterochromatin

Science.gov (United States)

Papait, Roberto; Pistore, Christian; Grazini, Ursula; Babbio, Federica; Cogliati, Sara; Pecoraro, Daniela; Brino, Laurent; Morand, Anne-Laure; Dechampesme, Anne-Marie; Spada, Fabio; Leonhardt, Heinrich; McBlane, Fraser; Oudet, Pierre

2008-01-01

Heterochromatic chromosomal regions undergo large-scale reorganization and progressively aggregate, forming chromocenters. These are dynamic structures that rapidly adapt to various stimuli that influence gene expression patterns, cell cycle progression, and differentiation. Np95-ICBP90 (m- and h-UHRF1) is a histone-binding protein expressed only in proliferating cells. During pericentromeric heterochromatin (PH) replication, Np95 specifically relocalizes to chromocenters where it highly concentrates in the replication factories that correspond to less compacted DNA. Np95 recruits HDAC and DNMT1 to PH and depletion of Np95 impairs PH replication. Here we show that Np95 causes large-scale modifications of chromocenters independently from the H3:K9 and H4:K20 trimethylation pathways, from the expression levels of HP1, from DNA methylation and from the cell cycle. The PHD domain is essential to induce this effect. The PHD domain is also required in vitro to increase access of a restriction enzyme to DNA packaged into nucleosomal arrays. We propose that the PHD domain of Np95-ICBP90 contributes to the opening and/or stabilization of dense chromocenter structures to support the recruitment of modifying enzymes, like HDAC and DNMT1, required for the replication and formation of PH. PMID:18508923

Detection of Brain Reorganization in Pediatric Multiple Sclerosis Using Functional MRI

Science.gov (United States)

2015-10-01

including the Wechsler Intelligence Scale for Children (WISC-IV) for verbal and non-verbal intelligence; the Boston Naming Test , which evaluates a...demonstrated congruency between fMRI mappings and patient performance; 2) testing of the fMRI methods we developed for use in POMS patients was carried out...adaptive functional reorganization as a way to explain how some early-stage MS patients are able to perform well in clinical cognitive testing

Seasonal atmospheric extinction

International Nuclear Information System (INIS)

Mikhail, J.S.

1979-01-01

Mean monochromatic extinction coefficients at various wavelengths at the Kottamia Observatory site have shown the existence of a seasonal variation of atmospheric extinction. The extinction of aerosol compontnts with wavelengths at winter represent exceedingly good conditions. Spring gives the highest extinction due to aerosol. (orig.)

Rotational reorganization of doped cholesteric liquid crystalline films

NARCIS (Netherlands)

Eelkema, R.; M. Pollard, M.; Katsonis, N.; Vicario, J.; J. Broer, D.; Feringa, B.L.

2006-01-01

In this paper an unprecedented rotational reorganization of cholesteric liquid crystalline films is described. This rotational reorganization results from the conversion of a chiral molecular motor dopant to an isomer with a different helical twisting power, leading to a change in the cholesteric

Acetylation-Dependent Chromatin Reorganization by BRDT, a Testis-Specific Bromodomain-Containing Protein

Science.gov (United States)

Pivot-Pajot, Christophe; Caron, Cécile; Govin, Jérôme; Vion, Alexandre; Rousseaux, Sophie; Khochbin, Saadi

2003-01-01

The association between histone acetylation and replacement observed during spermatogenesis prompted us to consider the testis as a source for potential factors capable of remodelling acetylated chromatin. A systematic search of data banks for open reading frames encoding testis-specific bromodomain-containing proteins focused our attention on BRDT, a testis-specific protein of unknown function containing two bromodomains. BRDT specifically binds hyperacetylated histone H4 tail depending on the integrity of both bromodomains. Moreover, in somatic cells, the ectopic expression of BRDT triggered a dramatic reorganization of the chromatin only after induction of histone hyperacetylation by trichostatin A (TSA). We then defined critical domains of BRDT involved in its activity. Both bromodomains of BRDT, as well as flanking regions, were found indispensable for its histone acetylation-dependent remodelling activity. Interestingly, we also observed that recombinant BRDT was capable of inducing reorganization of the chromatin of isolated nuclei in vitro only when the nuclei were from TSA-treated cells. This assay also allowed us to show that the action of BRDT was ATP independent, suggesting a structural role for the protein in the remodelling of acetylated chromatin. This is the first demonstration of a large-scale reorganization of acetylated chromatin induced by a specific factor. PMID:12861021

Long term fault system reorganization of convergent and strike-slip systems

Science.gov (United States)

Cooke, M. L.; McBeck, J.; Hatem, A. E.; Toeneboehn, K.; Beyer, J. L.

2017-12-01

Laboratory and numerical experiments representing deformation over many earthquake cycles demonstrate that fault evolution includes episodes of fault reorganization that optimize work on the fault system. Consequently, the mechanical and kinematic efficiencies of fault systems do not increase monotonically through their evolution. New fault configurations can optimize the external work required to accommodate deformation, suggesting that changes in system efficiency can drive fault reorganization. Laboratory evidence and numerical results show that fault reorganization within accretion, strike-slip and oblique convergent systems is associated with increasing efficiency due to increased fault slip (frictional work and seismic energy) and commensurate decreased off-fault deformation (internal work and work against gravity). Between episodes of fault reorganization, fault systems may become less efficient as they produce increasing off fault deformation. For example, laboratory and numerical experiments show that the interference and interaction between different fault segments may increase local internal work or that increasing convergence can increase work against gravity produced by a fault system. This accumulation of work triggers fault reorganization as stored work provides the energy required to grow new faults that reorganize the system to a more efficient configuration. The results of laboratory and numerical experiments reveal that we should expect crustal fault systems to reorganize following periods of increasing inefficiency, even in the absence of changes to the tectonic regime. In other words, fault reorganization doesn't require a change in tectonic loading. The time frame of fault reorganization depends on fault system configuration, strain rate and processes that relax stresses within the crust. For example, stress relaxation may keep pace with stress accumulation, which would limit the increase in the internal work and gravitational work so that

Elevational distribution and extinction risk in birds.

Directory of Open Access Journals (Sweden)

Rachel L White

Full Text Available Mountainous regions are hotspots of terrestrial biodiversity. Unlike islands, which have been the focus of extensive research on extinction dynamics, fewer studies have examined mountain ranges even though they face increasing threats from human pressures - notably habitat conversion and climate change. Limits to the taxonomic and geographical extent and resolution of previously available information have precluded an explicit assessment of the relative role of elevational distribution in determining extinction risk. We use a new global species-level avian database to quantify the influence of elevational distribution (range, maximum and midpoint on extinction risk in birds at the global scale. We also tested this relationship within biogeographic realms, higher taxonomic levels, and across phylogenetic contrasts. Potential confounding variables (i.e. phylogenetic, distributional, morphological, life history and niche breadth were also tested and controlled for. We show that the three measures of elevational distribution are strong negative predictors of avian extinction risk, with elevational range comparable and complementary to that of geographical range size. Extinction risk was also found to be positively associated with body weight, development and adult survival, but negatively associated with reproduction and niche breadth. The robust and consistent findings from this study demonstrate the importance of elevational distribution as a key driver of variation in extinction dynamics in birds. Our results also highlight elevational distribution as a missing criterion in current schemes for quantifying extinction risk and setting species conservation priorities in birds. Further research is recommended to test for generality across non-avian taxa, which will require an advance in our knowledge of species' current elevational ranges and increased efforts to digitise and centralise such data.

Broad-scale patterns of late jurassic dinosaur paleoecology.

Science.gov (United States)

Noto, Christopher R; Grossman, Ari

2010-09-03

There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure. This study applies Ecological Structure Analysis (ESA) to a dataset of 100+ dinosaur taxa arranged into twelve composite fossil assemblages from around the world. Each assemblage was assigned a climate zone (biome) based on its location. Dinosaur taxa were placed into ecomorphological categories. The proportion of each category creates an ecological profile for the assemblage, which were compared using cluster and principal components analyses. Assemblages grouped according to biome, with most coming from arid or semi-arid/seasonal climates. Differences between assemblages are tied to the proportion of large high-browsing vs. small ground-foraging herbivores, which separates arid from semi-arid and moister environments, respectively. However, the effects of historical, taphonomic, and other environmental factors are still evident. This study is the first to show that the general ecological structure of Late Jurassic dinosaur assemblages is preserved at large scales and can be assessed quantitatively. Despite a broad similarity of climatic conditions, a degree of ecological variation is observed between assemblages, from arid to moist. Taxonomic differences between Asia and the other regions demonstrate at least one case of ecosystem convergence. The proportion of different ecomorphs, which

Infrared Extinction and Stellar Populations in the Milky Way Midplane

Science.gov (United States)

Zasowski, Gail; Majewski, S. R.; Benjamin, R. A.; Nidever, D. L.; Skrutskie, M. F.; Indebetouw, R.; Patterson, R. J.; Meade, M. R.; Whitney, B. A.; Babler, B.; Churchwell, E.; Watson, C.

2012-01-01

The primary laboratory for developing and testing models of galaxy formation, structure, and evolution is our own Milky Way, the closest large galaxy and the only one in which we can resolve large numbers of individual stars. The recent availability of extensive stellar surveys, particularly infrared ones, has enabled precise, contiguous measurement of large-scale Galactic properties, a major improvement over inferences based on selected, but scattered, sightlines. However, our ability to fully exploit the Milky Way as a galactic laboratory is severely hampered by the fact that its midplane and central bulge -- where most of the Galactic stellar mass lies -- is heavily obscured by interstellar dust. Therefore, proper consideration of the interstellar extinction is crucial. This thesis describes a new extinction-correction method (the RJCE method) that measures the foreground extinction towards each star and, in many cases, enables recovery of its intrinsic stellar type. We have demonstrated the RJCE Method's validity and used it to produce new, reliable extinction maps of the heavily-reddened Galactic midplane. Taking advantage of the recovered stellar type information, we have generated maps probing the extinction at different heliocentric distances, thus yielding information on the elusive three-dimensional distribution of the interstellar dust. We also performed a study of the interstellar extinction law itself which revealed variations previously undetected in the diffuse ISM and established constraints on models of ISM grain formation and evolution. Furthermore, we undertook a study of large-scale stellar structure in the inner Galaxy -- the bar(s), bulge(s), and inner spiral arms. We used observed and extinction-corrected infrared photometry to map the coherent stellar features in these heavily-obscured parts of the Galaxy, placing constraints on models of the central stellar mass distribution.

Exploring Low Internal Reorganization Energies for Silicene Nanoclusters

KAUST Repository

Pablo-Pedro, Ricardo

2017-08-17

High-performance materials rely on small reorganization energies to facilitate both charge separation and charge transport. Here, we performed DFT calculations to predict small reorganization energies of rectangular silicene nanoclusters with hydrogen-passivated edges denoted by H-SiNC. We observe that across all geometries, H-SiNCs feature large electron affinities and highly stabilized anionic states, indicating their potential as n-type materials. Our findings suggest that fine-tuning the size of H-SiNCs along the zigzag and armchair directions may permit the design of novel n-type electronic materials and spinctronics devices that incorporate both high electron affinities and very low internal reorganization energies.

Climate-Related Local Extinctions Are Already Widespread among Plant and Animal Species.

Directory of Open Access Journals (Sweden)

John J Wiens

2016-12-01

Full Text Available Current climate change may be a major threat to global biodiversity, but the extent of species loss will depend on the details of how species respond to changing climates. For example, if most species can undergo rapid change in their climatic niches, then extinctions may be limited. Numerous studies have now documented shifts in the geographic ranges of species that were inferred to be related to climate change, especially shifts towards higher mean elevations and latitudes. Many of these studies contain valuable data on extinctions of local populations that have not yet been thoroughly explored. Specifically, overall range shifts can include range contractions at the "warm edges" of species' ranges (i.e., lower latitudes and elevations, contractions which occur through local extinctions. Here, data on climate-related range shifts were used to test the frequency of local extinctions related to recent climate change. The results show that climate-related local extinctions have already occurred in hundreds of species, including 47% of the 976 species surveyed. This frequency of local extinctions was broadly similar across climatic zones, clades, and habitats but was significantly higher in tropical species than in temperate species (55% versus 39%, in animals than in plants (50% versus 39%, and in freshwater habitats relative to terrestrial and marine habitats (74% versus 46% versus 51%. Overall, these results suggest that local extinctions related to climate change are already widespread, even though levels of climate change so far are modest relative to those predicted in the next 100 years. These extinctions will presumably become much more prevalent as global warming increases further by roughly 2-fold to 5-fold over the coming decades.

Evidence for local and global redox conditions at an Early Ordovician (Tremadocian) mass extinction

Science.gov (United States)

Edwards, Cole T.; Fike, David A.; Saltzman, Matthew R.; Lu, Wanyi; Lu, Zunli

2018-01-01

Profound changes in environmental conditions, particularly atmospheric oxygen levels, are thought to be important drivers of several major biotic events (e.g. mass extinctions and diversifications). The early Paleozoic represents a key interval in the oxygenation of the ocean-atmosphere system and evolution of the biosphere. Global proxies (e.g. carbon (δ13C) and sulfur (δ34S) isotopes) are used to diagnose potential changes in oxygenation and infer causes of environmental change and biotic turnover. The Cambrian-Ordovician contains several trilobite extinctions (some are apparently local, but others are globally correlative) that are attributed to anoxia based on coeval positive δ13C and δ34S excursions. These extinction and excursion events have yet to be coupled with more recently developed proxies thought to be more reflective of local redox conditions in the water column (e.g. I/Ca) to confirm whether these extinctions were associated with oxygen crises over a regional or global scale. Here we examine an Early Ordovician (Tremadocian Stage) extinction event previously interpreted to reflect a continuation of recurrent early Paleozoic anoxic events that expanded into nearshore environments. δ13C, δ34S, and I/Ca trends were measured from three sections in the Great Basin region to test whether I/Ca trends support the notion that anoxia was locally present in the water column along the Laurentian margin. Evidence for anoxia is based on coincident, but not always synchronous, positive δ13C and δ34S excursions (mainly from carbonate-associated sulfate and less so from pyrite data), a 30% extinction of standing generic diversity, and near-zero I/Ca values. Although evidence for local water column anoxia from the I/Ca proxy broadly agrees with intervals of global anoxia inferred from δ13C and δ34S trends, a more complex picture is evident where spatially and temporally variable local trends are superimposed on time-averaged global trends. Stratigraphic

Mathematical Modeling of Extinction of Inhomogeneous Populations

Science.gov (United States)

Karev, G.P.; Kareva, I.

2016-01-01

Mathematical models of population extinction have a variety of applications in such areas as ecology, paleontology and conservation biology. Here we propose and investigate two types of sub-exponential models of population extinction. Unlike the more traditional exponential models, the life duration of sub-exponential models is finite. In the first model, the population is assumed to be composed clones that are independent from each other. In the second model, we assume that the size of the population as a whole decreases according to the sub-exponential equation. We then investigate the “unobserved heterogeneity”, i.e. the underlying inhomogeneous population model, and calculate the distribution of frequencies of clones for both models. We show that the dynamics of frequencies in the first model is governed by the principle of minimum of Tsallis information loss. In the second model, the notion of “internal population time” is proposed; with respect to the internal time, the dynamics of frequencies is governed by the principle of minimum of Shannon information loss. The results of this analysis show that the principle of minimum of information loss is the underlying law for the evolution of a broad class of models of population extinction. Finally, we propose a possible application of this modeling framework to mechanisms underlying time perception. PMID:27090117

Extinction risk under coloured environmental noise

OpenAIRE

Heino, M; Ripa, Jörgen; Kaitala, V

2000-01-01

Positively autocorrelated red environmental noise is characterized by a strong dependence of expected sample variance on sample length. This dependence has to be taken into account when assessing extinction risk under red and white uncorrelated environmental noise. To facilitate a comparison between red and white noise, their expected variances can be scaled to be equal, but only at a chosen time scale. We show with a simple one-dimensional population dynamics model that the different but equ...

Global Dynamic Numerical Simulations of Plate Tectonic Reorganizations

Science.gov (United States)

Morra, G.; Quevedo, L.; Butterworth, N.; Matthews, K. J.; Müller, D.

2010-12-01

We use a new numerical approach for global geodynamics to investigate the origin of present global plate motion and to identify the causes of the last two global tectonic reorganizations occurred about 50 and 100 million years ago (Ma) [1]. While the 50 Ma event is the most well-known global plate-mantle event, expressed by the bend in the Hawaiian-Emperor volcanic chain, a prominent plate reorganization at about 100 Ma, although presently little studied, is clearly indicated by a major bend in the fracture zones in the Indian Ocean and by a change in Pacific plate motion [2]. Our workflow involves turning plate reconstructions into surface meshes that are subsequently employed as initial conditions for global Boundary Element numerical models. The tectonic setting that anticipates the reorganizations is processed with the software GPlates, combining the 3D mesh of the paleo-plate morphology and the reconstruction of paleo-subducted slabs, elaborated from tectonic history [3]. All our models involve the entire planetary system, are fully dynamic, have free surface, are characterized by a spectacular computational speed due to the simultaneous use of the multi-pole algorithm and the Boundary Element formulation and are limited only by the use of sharp material property variations [4]. We employ this new tool to unravel the causes of plate tectonic reorganizations, producing and comparing global plate motion with the reconstructed ones. References: [1] Torsvik, T., Müller, R.D., Van der Voo, R., Steinberger, B., and Gaina, C., 2008, Global Plate Motion Frames: Toward a unified model: Reviews in Geophysics, VOL. 46, RG3004, 44 PP., 2008 [2] Wessel, P. and Kroenke, L.W. Pacific absolute plate motion since 145 Ma: An assessment of the fixed hot spot hypothesis. Journal of Geophysical Research, Vol 113, B06101, 2008 [3] L. Quevedo, G. Morra, R. D. Mueller. Parallel Fast Multipole Boundary Element Method for Crustal Dynamics, Proceeding 9th World Congress and 4th Asian

Understanding extreme sea levels for broad-scale coastal impact and adaptation analysis

Science.gov (United States)

Wahl, T.; Haigh, I. D.; Nicholls, R. J.; Arns, A.; Dangendorf, S.; Hinkel, J.; Slangen, A. B. A.

2017-07-01

One of the main consequences of mean sea level rise (SLR) on human settlements is an increase in flood risk due to an increase in the intensity and frequency of extreme sea levels (ESL). While substantial research efforts are directed towards quantifying projections and uncertainties of future global and regional SLR, corresponding uncertainties in contemporary ESL have not been assessed and projections are limited. Here we quantify, for the first time at global scale, the uncertainties in present-day ESL estimates, which have by default been ignored in broad-scale sea-level rise impact assessments to date. ESL uncertainties exceed those from global SLR projections and, assuming that we meet the Paris agreement goals, the projected SLR itself by the end of the century in many regions. Both uncertainties in SLR projections and ESL estimates need to be understood and combined to fully assess potential impacts and adaptation needs.

Bimodal extinction without cross-modal extinction.

OpenAIRE

Inhoff, A W; Rafal, R D; Posner, M J

1992-01-01

Three patients with unilateral neurological injury were clinically examined. All showed consistent unilateral extinction in the tactile and visual modalities on simultaneous intramodal stimulation. There was virtually no evidence for cross-modal extinction, however, so that contralateral stimulation of one modality would have extinguished perception of ipsilateral stimuli in the other modality. It is concluded that the attentional system controlling the encoding of tactile and visual stimuli ...

Rethinking Trade-Driven Extinction Risk in Marine and Terrestrial Megafauna.

Science.gov (United States)

McClenachan, Loren; Cooper, Andrew B; Dulvy, Nicholas K

2016-06-20

Large animals hunted for the high value of their parts (e.g., elephant ivory and shark fins) are at risk of extinction due to both intensive international trade pressure and intrinsic biological sensitivity. However, the relative role of trade, particularly in non-perishable products, and biological factors in driving extinction risk is not well understood [1-4]. Here we identify a taxonomically diverse group of >100 marine and terrestrial megafauna targeted for international luxury markets; estimate their value across three points of sale; test relationships among extinction risk, high value, and body size; and quantify the effects of two mitigating factors: poaching fines and geographic range size. We find that body size is the principal driver of risk for lower value species, but that this biological pattern is eliminated above a value threshold, meaning that the most valuable species face a high extinction risk regardless of size. For example, once mean product values exceed US$12,557 kg(-1), body size no longer drives risk. Total value scales with size for marine animals more strongly than for terrestrial animals, incentivizing the hunting of large marine individuals and species. Poaching fines currently have little effect on extinction risk; fines would need to be increased 10- to 100-fold to be effective. Large geographic ranges reduce risk for terrestrial, but not marine, species, whose ranges are ten times greater. Our results underscore both the evolutionary and ecosystem consequences of targeting large marine animals and the need to geographically scale up and prioritize conservation of high-value marine species to avoid extinction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rethinking Extinction

OpenAIRE

Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

2015-01-01

Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavior...

The Class I HDAC Inhibitor RGFP963 Enhances Consolidation of Cued Fear Extinction

Science.gov (United States)

Bowers, Mallory E.; Xia, Bing; Carreiro, Samantha; Ressler, Kerry J.

2015-01-01

Evidence indicates that broad, nonspecific histone deacetylase (HDAC) inhibition enhances learning and memory, however, the contribution of the various HDACs to specific forms of learning is incompletely understood. Here, we show that the Class I HDAC inhibitor, RGFP963, enhances consolidation of cued fear extinction. However, RGFP966, a strong…

Modeling galactic extinction

OpenAIRE

Cecchi-Pestellini, C.; Mulas, G.; Casu, S.; Iatì, M. A.; Saija, R.; Cacciola, A.; Borghese, F.; Denti, P.

2011-01-01

We present a model for interstellar extinction dust, in which we assume a bimodal distribution of extinction carriers, a dispersion of core-mantle grains, supplemented by a collection of PAHs in free molecular form. We use state-of-the-art methods to calculate the extinction due to macroscopic dust particles, and the absorption cross-sections of PAHs in four different charge states. While successfull for most of observed Galactic extinction curves, in few cases the model cannot provide reliab...

Exploring Low Internal Reorganization Energies for Silicene Nanoclusters

Science.gov (United States)

Pablo-Pedro, Ricardo; Lopez-Rios, Hector; Mendoza-Cortes, Jose-L.; Kong, Jing; Fomine, Serguei; Van Voorhis, Troy; Dresselhaus, Mildred S.

2018-05-01

This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. High-performance materials rely on small reorganization energies to facilitate both charge separation and charge transport. Here, we perform density-functional-theory calculations to predict small reorganization energies of rectangular silicene nanoclusters with hydrogen-passivated edges denoted by H-SiNC. We observe that across all geometries, H-SiNCs feature large electron affinities and highly stabilized anionic states, indicating their potential as n -type materials. Our findings suggest that fine-tuning the size of H-SiNCs along the "zigzag" and "armchair" directions may permit the design of novel n -type electronic materials and spintronics devices that incorporate both high electron affinities and very low internal reorganization energies.

Ultraviolet photometry from the orbiting astronomical observatory. XX. The ultraviolet extinction bump

International Nuclear Information System (INIS)

Savage, B.D.

1975-01-01

Interstellar extinction curves over the wavelength region 1800--3600 A are presented for 36 stars. The stars have E (B-V) in the range 0.03 to 0.55, and are mostly confined to the brighter OB associations distributed along the plane of the Galaxy. Every extinction curve exhibits a broad extinction bump peaking near 2175 A (4.6 μ -1 ). The position of the peak and the profile of the feature appear remarkably constant among the sample of stars. With only a few exceptions, E (lambda)-3320, a measure of the strength of the feature, correlates very well with E (B-V), implying that the bump has an interstellar rather than a circumstellar origin. The observation that the bump position and shape are constant, or very nearly constant, places severe restrictions on the grain geometrical parameters if the feature is to be explained by classical scattering theory employing bulk optical constants. In fact, the restrictions are so severe that an alternate explanation seems to be required unless the dust grains that exist in widely separated regions of space and under very different physical conditions have nearly identical size and shape distributions. Three extinction curves that extend to 1100 A are also presented. These curves show the same general extinction characteristics reported earlier. The curve for 22 Sco provides another example of a star that is []physically associated with nebulosity and that also has abnormally low far-ultraviolet extinction. We have searched the extinction curves for fine structure such as abrupt slope changes or new diffuse interstellar features. Unfortunately, there is no convincing evidence for such structure over the interval 1800--3600 A. (auth)

Epidemic extinction paths in complex networks

Science.gov (United States)

Hindes, Jason; Schwartz, Ira B.

2017-05-01

We study the extinction of long-lived epidemics on finite complex networks induced by intrinsic noise. Applying analytical techniques to the stochastic susceptible-infected-susceptible model, we predict the distribution of large fluctuations, the most probable or optimal path through a network that leads to a disease-free state from an endemic state, and the average extinction time in general configurations. Our predictions agree with Monte Carlo simulations on several networks, including synthetic weighted and degree-distributed networks with degree correlations, and an empirical high school contact network. In addition, our approach quantifies characteristic scaling patterns for the optimal path and distribution of large fluctuations, both near and away from the epidemic threshold, in networks with heterogeneous eigenvector centrality and degree distributions.

Large extents of intensive land use limit community reorganization during climate warming.

Science.gov (United States)

Oliver, Tom H; Gillings, Simon; Pearce-Higgins, James W; Brereton, Tom; Crick, Humphrey Q P; Duffield, Simon J; Morecroft, Michael D; Roy, David B

2017-06-01

Climate change is increasingly altering the composition of ecological communities, in combination with other environmental pressures such as high-intensity land use. Pressures are expected to interact in their effects, but the extent to which intensive human land use constrains community responses to climate change is currently unclear. A generic indicator of climate change impact, the community temperature index (CTI), has previously been used to suggest that both bird and butterflies are successfully 'tracking' climate change. Here, we assessed community changes at over 600 English bird or butterfly monitoring sites over three decades and tested how the surrounding land has influenced these changes. We partitioned community changes into warm- and cold-associated assemblages and found that English bird communities have not reorganized successfully in response to climate change. CTI increases for birds are primarily attributable to the loss of cold-associated species, whilst for butterflies, warm-associated species have tended to increase. Importantly, the area of intensively managed land use around monitoring sites appears to influence these community changes, with large extents of intensively managed land limiting 'adaptive' community reorganization in response to climate change. Specifically, high-intensity land use appears to exacerbate declines in cold-adapted bird and butterfly species, and prevent increases in warm-associated birds. This has broad implications for managing landscapes to promote climate change adaptation. © 2017 John Wiley & Sons Ltd.

Expediting Scientific Data Analysis with Reorganization of Data

Energy Technology Data Exchange (ETDEWEB)

Byna, Surendra; Wu, Kesheng

2013-08-19

Data producers typically optimize the layout of data files to minimize the write time. In most cases, data analysis tasks read these files in access patterns different from the write patterns causing poor read performance. In this paper, we introduce Scientific Data Services (SDS), a framework for bridging the performance gap between writing and reading scientific data. SDS reorganizes data to match the read patterns of analysis tasks and enables transparent data reads from the reorganized data. We implemented a HDF5 Virtual Object Layer (VOL) plugin to redirect the HDF5 dataset read calls to the reorganized data. To demonstrate the effectiveness of SDS, we applied two parallel data organization techniques: a sort-based organization on a plasma physics data and a transpose-based organization on mass spectrometry imaging data. We also extended the HDF5 data access API to allow selection of data based on their values through a query interface, called SDS Query. We evaluated the execution time in accessing various subsets of data through existing HDF5 Read API and SDS Query. We showed that reading the reorganized data using SDS is up to 55X faster than reading the original data.

High-precision U-Pb zircon geochronological constraints on the End-Triassic Mass Extinction, the late Triassic Astronomical Time Scale and geochemical evolution of CAMP magmatism

Science.gov (United States)

Blackburn, T. J.; Olsen, P. E.; Bowring, S. A.; McLean, N. M.; Kent, D. V.; Puffer, J. H.; McHone, G.; Rasbury, T.

2012-12-01

for eight CAMP flows and sills from the eastern U.S. and Morocco. These data are used first to independently test the astronomically calibrated time scale and sediment accumulation rates within the Triassic-Jurassic rift basins along the eastern North America. The U-Pb, paleontological, magnetostratigraphic and astronomical data are combined to constrain the onset and duration of the CAMP and clarify the temporal relationship between the CAMP and the ETE. The dataset together allows more precise estimates of eruptive volume per unit time, a requirement for rigorous evaluation of climate-driven models for the extinction.

Long-term maintenance of immediate or delayed extinction is determined by the extinction-test interval

OpenAIRE

Johnson, Justin S.; Escobar, Martha; Kimble, Whitney L.

2010-01-01

Short acquisition-extinction intervals (immediate extinction) can lead to either more or less spontaneous recovery than long acquisition-extinction intervals (delayed extinction). Using rat subjects, we observed less spontaneous recovery following immediate than delayed extinction (Experiment 1). However, this was the case only if a relatively long extinction-test interval was used; a relatively short extinction-test interval yielded the opposite result (Experiment 2). Previous data appear co...

Differences in Brain Adaptive Functional Reorganization in Right and Left Total Brachial Plexus Injury Patients.

Science.gov (United States)

Feng, Jun-Tao; Liu, Han-Qiu; Xu, Jian-Guang; Gu, Yu-Dong; Shen, Yun-Dong

2015-09-01

Total brachial plexus avulsion injury (BPAI) results in the total functional loss of the affected limb and induces extensive brain functional reorganization. However, because the dominant hand is responsible for more cognitive-related tasks, injuries on this side induce more adaptive changes in brain function. In this article, we explored the differences in brain functional reorganization after injuries in unilateral BPAI patients. We applied resting-state functional magnetic resonance imaging scanning to 10 left and 10 right BPAI patients and 20 healthy control subjects. The amplitude of low-frequency fluctuation (ALFF), which is a resting-state index, was calculated for all patients as an indication of the functional activity level of the brain. Two-sample t-tests were performed between left BPAI patients and controls, right BPAI patients and controls, and between left and right BPAI patients. Two-sample t-tests of the ALFF values revealed that right BPAIs induced larger scale brain reorganization than did left BPAIs. Both left and right BPAIs elicited a decreased ALFF value in the right precuneus (P right BPAI patients exhibited increased ALFF values in a greater number of brain regions than left BPAI patients, including the inferior temporal gyrus, lingual gyrus, calcarine sulcus, and fusiform gyrus. Our results revealed that right BPAIs induced greater extents of brain functional reorganization than left BPAIs, which reflected the relatively more extensive adaptive process that followed injuries of the dominant hand. Copyright © 2015 Elsevier Inc. All rights reserved.

Polarized neutron diffraction - a tool for testing extinction models: application to yttrium iron garnet

International Nuclear Information System (INIS)

Bonnet, M.; Delapalme, A.; Becker, P.

1976-01-01

This paper shows that polarized neutron experiments, which do not depend on any scale factor, are very dependent on extinction and provide original tests for extinction models. Moon, Koehler, Cable and Child (1972) have formulated the problem and proposed a first-order solution applicable only when the extinction is small. In the first part, some analytical derivations of secondary extinction corrections are discussed, using the formalism of Becker and Coppens (1974). In the second part, the main principles governing polarized neutron diffraction are briefly reviewed, with a special discussion of extinction problems. The method is then applied to the case of yttrium iron garnet (YIG). This experiment shows the technique of polarized neutrons to be very powerful for testing extinction models and for deciding whether the crystal behaves dynamically or kinematically (following Kato's criterion). (Auth.)

Interstellar extinction correlations

International Nuclear Information System (INIS)

Jones, A.P.; Williams, D.A.; Duley, W.W.

1987-01-01

A recently proposed model for interstellar grains in which the extinction arises from small silicate cores with mantles of hydrogenated amorphous carbon (HAC or α-C:H), and large, but thinly coated, silicate grains can successfully explain many of the observed properties of interstellar dust. The small silicate cores give rise to the 2200 A extinction feature. The extinction in the visual is produced by the large silicates and the HAC mantles on the small cores, whilst the far UV extinction arises in the HAC mantles with a small contribution form the silicate grains. The grain model requires that the silicate material is the more resilient component and that variations in the observed extinction from region to region are due to the nature and depletion of the carbon in the HAC mantles. (author)

Extinction threshold of a population in spatial and stochastic model

OpenAIRE

Soroka, Yevheniia; Rublyov, Bogdan

2016-01-01

In this study, spatial stochastic and logistic model (SSLM) describing dynamics of a population of a certain species was analysed. The behaviour of the extinction threshold as a function of model parameters was studied. More specifically, we studied how the critical values for the model parameters that separate the cases of extinction and persistence depend on the spatial scales of the competition and dispersal kernels. We compared the simulations and analytical results to examine if and how ...

Parameterization of the Extinction Coefficient in Ice and Mixed-Phase Arctic Clouds during the ISDAC Field Campaign

Energy Technology Data Exchange (ETDEWEB)

Korolev, A; Shashkov, A; Barker, H

2012-03-06

This report documents the history of attempts to directly measure cloud extinction, the current measurement device known as the Cloud Extinction Probe (CEP), specific problems with direct measurement of extinction coefficient, and the attempts made here to address these problems. Extinction coefficient is one of the fundamental microphysical parameters characterizing bulk properties of clouds. Knowledge of extinction coefficient is of crucial importance for radiative transfer calculations in weather prediction and climate models given that Earth's radiation budget (ERB) is modulated much by clouds. In order for a large-scale model to properly account for ERB and perturbations to it, it must ultimately be able to simulate cloud extinction coefficient well. In turn this requires adequate and simultaneous simulation of profiles of cloud water content and particle habit and size. Similarly, remote inference of cloud properties requires assumptions to be made about cloud phase and associated single-scattering properties, of which extinction coefficient is crucial. Hence, extinction coefficient plays an important role in both application and validation of methods for remote inference of cloud properties from data obtained from both satellite and surface sensors (e.g., Barker et al. 2008). While estimation of extinction coefficient within large-scale models is relatively straightforward for pure water droplets, thanks to Mie theory, mixed-phase and ice clouds still present problems. This is because of the myriad forms and sizes that crystals can achieve, each having their own unique extinction properties. For the foreseeable future, large-scale models will have to be content with diagnostic parametrization of crystal size and type. However, before they are able to provide satisfactory values needed for calculation of radiative transfer, they require the intermediate step of assigning single-scattering properties to particles. The most basic of these is extinction

Mirror therapy in lower limb amputees. A look beyond primary motor cortex reorganization

Energy Technology Data Exchange (ETDEWEB)

Seidel, S.; Essmeister, M.; Sycha, T.; Auff, E. [Vienna Medical Univ. (Austria). Dept. of Neurology; Kasprian, G.; Furtner, J.; Schoepf, V.; Prayer, D. [Vienna Medical Univ. (Austria). Dept. of Neuroradiology

2011-11-15

Phantom pain in upper limb amputees is associated with the extent of reorganization in the primary sensorimotor cortex. Mirror visual feedback therapy has been shown to improve phantom pain. We investigated the extent of cortical reorganization in lower limb amputees and changes in neural activity induced by mirror therapy. Eight lower limb amputees underwent 12 sessions of MVFT and functional magnetic resonance imaging (fMRI) of the brain before the first and after the last MVFT session. FMRI sessions consisted of two runs in which subjects were instructed to perform repetitive movement of the healthy and phantom ankle. Before MVFT, the mean phantom pain intensity was 4.6 {+-} 3.1 on a visual analog scale and decreased to 1.8 {+-} 1.7 (p = 0.04). We did not observe a consistent pattern of cortical activation in primary sensorimotor areas during phantom limb movements. Following MVFT, increased activity was obtained in the right orbitofrontal cortex during phantom ankle movements. Comparison of cortical activity during movements of the phantom ankle and the intact ankle showed significantly higher activity in the left inferior frontal cortex (pars triangularis). These results question the known association between phantom pain and primary sensorimotor reorganization and propose reorganizational changes involving multiple cortical areas in lower limb amputees. Finally, reduction of phantom pain after mirror visual feedback therapy was associated with increased prefrontal cortical activity during phantom ankle movements. (orig.)

Facilitation of extinction and re-extinction of operant behavior in mice by chlordiazepoxide and D-cycloserine.

Science.gov (United States)

Leslie, Julian C; Norwood, Kelly

2013-05-01

The aim was to compare operant extinction with re-extinction following re-acquisition and to investigate neuropharmacological mechanisms through administration of drugs potentiating GABAergic or glutamatergic systems. Groups of C57Bl/6 mice were trained to lever press for food on a fixed ratio schedule, then extinguished with or without pre-session chlordiazepoxide or post-session d-cycloserine administration (15mg/kg in each case), then retrained to lever press for food, then re-extinguished with or without pre-session chlordiazepoxide or post-session d-cycloserine. Under vehicle injections, extinction and re-extinction curves were indistinguishable, but drug treatments showed that there was less resistance to extinction in the re-extinction phase. Chlordiazepoxide facilitated extinction and re-extinction, with an earlier effect during re-extinction. d-Cycloserine also facilitated extinction and re-extinction, with some evidence of an earlier effect during re-extinction. These results replicate and extend earlier findings with operant extinction, but differ from some previous reports of d-cycloserine on re-extinction of Pavlovian conditioned fear. Implications for accounts of the similarities and differences between neural mechanisms of extinction following either Pavlovian or operant conditioning, and applications of these findings, are discussed. Copyright © 2013 Elsevier Inc. All rights reserved.

Ultraviolet Extinction in Backlit Galaxies - from Galaxy Zoo to GALEX

Science.gov (United States)

Keel, William C.; Manning, A.; Holwerda, B. W.; Lintott, C.; Schawinski, K.; Galaxy Zoo Team

2012-01-01

We examine the ultraviolet extinction of galaxies on large scales, combining optical and GALEX UV data on backlit galaxies (most found in the Galaxy Zoo citizen-science project). We analyze the images in matching ways, modelling both foreground and background galaxies by symmetry or elliptical isophote families as appropriate, and using the non-overlapping regions of the galaxies to estimate errors in the derived transmission T=e-κ. Spirals appear less symmetric in the UV, as star-forming regions become more dominant, so that our most reliable results are mean values across multiple regions and multiple galaxies. Our mean effective extinction curve is dominated by the contribution of luminous spirals,and shows a fairly flat gray" extinction law into the ultraviolet. For example, the median of κNUV/κB in spiral arms is only 1.3. Along with previous high-resolution HST studies of a few nearby backlit galaxies, this suggests that on kpc scales the effective extinction is dominated by the dust clumping rather than the intrinsic reddening law. This implies that extrapolation of local properties to short wavelengths, a step toward the history of dust in galaxies through comparison of local properties with a similar analysis in deep HST fields, can be done without introducing much additional error. This work was supported by NASA Astrophysics Data Analysis Program grant NNX10AD54G.

Long-Term Maintenance of Immediate or Delayed Extinction Is Determined by the Extinction-Test Interval

Science.gov (United States)

Johnson, Justin S.; Escobar, Martha; Kimble, Whitney L.

2010-01-01

Short acquisition-extinction intervals (immediate extinction) can lead to either more or less spontaneous recovery than long acquisition-extinction intervals (delayed extinction). Using rat subjects, we observed less spontaneous recovery following immediate than delayed extinction (Experiment 1). However, this was the case only if a relatively…

Theoretical study of substitution effects on molecular reorganization energy in organic semiconductors.

Science.gov (United States)

Geng, Hua; Niu, Yingli; Peng, Qian; Shuai, Zhigang; Coropceanu, Veaceslav; Brédas, Jean-Luc

2011-09-14

Chemical substitutions are powerful molecular design tools to enhance the performance of organic semiconductors, for instance, to improve solubility, intermolecular stacking, or film quality. However, at the microscopic level, substitutions in general tend to increase the molecular reorganization energy and thus decrease the intrinsic charge-carrier mobility. Through density functional theory calculations, we elucidate strategies that could be followed to reduce the reorganization energy upon chemical substitution. Specific examples are given here for hole-transport materials including indolo-carbazoles and several triarylamine derivatives. Through decomposition of the total reorganization energy into the internal coordinate space, we are able to identify the molecular segment that provides the most important contributions to the reorganization energy. It is found that when substitution reduces (enhances) the amplitude of the relevant frontier molecular orbital in that segment, the total reorganization energy decreases (increases). In particular, chlorination at appropriate positions can significantly reduce the reorganization energy. Several other substituents are shown to play a similar role, to a greater or lesser extent. © 2011 American Institute of Physics

USING M DWARF SPECTRA TO MAP EXTINCTION IN THE LOCAL GALAXY

International Nuclear Information System (INIS)

Jones, David O.; West, Andrew A.; Foster, Jonathan B.

2011-01-01

We use spectra of more than 56,000 M dwarfs from the Sloan Digital Sky Survey (SDSS) to create a high-latitude extinction map of the local Galaxy. Our technique compares spectra from the stars in the SDSS Data Release 7 M dwarf sample in low-extinction lines of sight, as determined by Schlegel et al., to other SDSS M dwarf spectra in order to derive improved distance estimates and accurate line-of-sight extinctions. Unlike most previous studies, which have used a two-color method to determine extinction, we fit extinction curves to fluxes across the spectral range from 5700 to 9200 A for every star in our sample. Our result is an A V map that extends from a few tens of pc to approximately 2 kpc away from the Sun. We also use a similar technique to create a map of R V values within approximately 1 kpc of the Sun and find that they are consistent with the widely accepted diffuse interstellar medium value of 3.1. Using our extinction data, we derive a dust scale height for the local Galaxy of 119 ± 15 pc and find evidence for a local dust cavity.

Extinction and the fossil record

Science.gov (United States)

Sepkoski, J. J. Jr; Sepkoski JJ, ,. J. r. (Principal Investigator)

1994-01-01

The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction.

Extinctions. Paleontological baselines for evaluating extinction risk in the modern oceans.

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Finnegan, Seth; Anderson, Sean C; Harnik, Paul G; Simpson, Carl; Tittensor, Derek P; Byrnes, Jarrett E; Finkel, Zoe V; Lindberg, David R; Liow, Lee Hsiang; Lockwood, Rowan; Lotze, Heike K; McClain, Craig R; McGuire, Jenny L; O'Dea, Aaron; Pandolfi, John M

2015-05-01

Marine taxa are threatened by anthropogenic impacts, but knowledge of their extinction vulnerabilities is limited. The fossil record provides rich information on past extinctions that can help predict biotic responses. We show that over 23 million years, taxonomic membership and geographic range size consistently explain a large proportion of extinction risk variation in six major taxonomic groups. We assess intrinsic risk-extinction risk predicted by paleontologically calibrated models-for modern genera in these groups. Mapping the geographic distribution of these genera identifies coastal biogeographic provinces where fauna with high intrinsic risk are strongly affected by human activity or climate change. Such regions are disproportionately in the tropics, raising the possibility that these ecosystems may be particularly vulnerable to future extinctions. Intrinsic risk provides a prehuman baseline for considering current threats to marine biodiversity. Copyright © 2015, American Association for the Advancement of Science.

Theory of invasion extinction dynamics in minimal food webs

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Haerter, Jan O.; Mitarai, Namiko; Sneppen, Kim

2018-02-01

When food webs are exposed to species invasion, secondary extinction cascades may be set off. Although much work has gone into characterizing the structure of food webs, systematic predictions on their evolutionary dynamics are still scarce. Here we present a theoretical framework that predicts extinctions in terms of an alternating sequence of two basic processes: resource depletion by or competitive exclusion between consumers. We first propose a conceptual invasion extinction model (IEM) involving random fitness coefficients. We bolster this IEM by an analytical, recursive procedure for calculating idealized extinction cascades after any species addition and simulate the long-time evolution. Our procedure describes minimal food webs where each species interacts with only a single resource through the generalized Lotka-Volterra equations. For such food webs ex- tinction cascades are determined uniquely and the system always relaxes to a stable steady state. The dynamics and scale invariant species life time resemble the behavior of the IEM, and correctly predict an upper limit for trophic levels as observed in the field.

Sexual selection affects local extinction and turnover in bird communities

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Doherty, P.F.; Sorci, G.; Royle, J. Andrew; Hines, J.E.; Nichols, J.D.; Boulinier, T.

2003-01-01

Predicting extinction risks has become a central goal for conservation and evolutionary biologists interested in population and community dynamics. Several factors have been put forward to explain risks of extinction, including ecological and life history characteristics of individuals. For instance, factors that affect the balance between natality and mortality can have profound effects on population persistence. Sexual selection has been identified as one such factor. Populations under strong sexual selection experience a number of costs ranging from increased predation and parasitism to enhanced sensitivity to environmental and demographic stochasticity. These findings have led to the prediction that local extinction rates should be higher for species/populations with intense sexual selection. We tested this prediction by analyzing the dynamics of natural bird communities at a continental scale over a period of 21 years (1975-1996), using relevant statistical tools. In agreement with the theoretical prediction, we found that sexual selection increased risks of local extinction (dichromatic birds had on average a 23% higher local extinction rate than monochromatic species). However, despite higher local extinction probabilities, the number of dichromatic species did not decrease over the period considered in this study. This pattern was caused by higher local turnover rates of dichromatic species, resulting in relatively stable communities for both groups of species. Our results suggest that these communities function as metacommunities, with frequent local extinctions followed by colonization. Anthropogenic factors impeding dispersal might therefore have a significant impact on the global persistence of sexually selected species.

Metapopulation extinction risk: dispersal's duplicity.

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Higgins, Kevin

2009-09-01

Metapopulation extinction risk is the probability that all local populations are simultaneously extinct during a fixed time frame. Dispersal may reduce a metapopulation's extinction risk by raising its average per-capita growth rate. By contrast, dispersal may raise a metapopulation's extinction risk by reducing its average population density. Which effect prevails is controlled by habitat fragmentation. Dispersal in mildly fragmented habitat reduces a metapopulation's extinction risk by raising its average per-capita growth rate without causing any appreciable drop in its average population density. By contrast, dispersal in severely fragmented habitat raises a metapopulation's extinction risk because the rise in its average per-capita growth rate is more than offset by the decline in its average population density. The metapopulation model used here shows several other interesting phenomena. Dispersal in sufficiently fragmented habitat reduces a metapopulation's extinction risk to that of a constant environment. Dispersal between habitat fragments reduces a metapopulation's extinction risk insofar as local environments are asynchronous. Grouped dispersal raises the effective habitat fragmentation level. Dispersal search barriers raise metapopulation extinction risk. Nonuniform dispersal may reduce the effective fraction of suitable habitat fragments below the extinction threshold. Nonuniform dispersal may make demographic stochasticity a more potent metapopulation extinction force than environmental stochasticity.

Species Turnover through Time: Colonization and Extinction Dynamics across Metacommunities.

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Nuvoloni, Felipe Micali; Feres, Reinaldo José Fazzio; Gilbert, Benjamin

2016-06-01

Island biogeography and metacommunity theory often use equilibrium assumptions to predict local diversity, yet nonequilibrium dynamics are common in nature. In nonequilibrium communities, local diversity fluctuates through time as the relative importance of colonization and extinction change. Here, we test the prevalence and causes of nonequilibrium dynamics in metacommunities of mites associated with rubber trees distributed over large spatial (>1,000 km) and temporal (>30-60 generations) scales in Brazil. We measured colonization and extinction rates to test species turnover and nonequilibrium dynamics over a growing season. Mite metacommunities exhibited nonequilibrium dynamics for most months of the year, and these dynamics tracked climatic conditions. Monthly shifts in temperature of more than 1°C resulted in nonequilibrium dynamics, as did mean temperatures outside of two critical ranges. Nonequilibrium dynamics were caused by a change in colonization with temperature change and changes in both colonization and extinction with absolute temperature. Species turnover showed different trends; high relative humidity increased both colonization and extinction rates, increasing turnover but not nonequilibrium dynamics. Our study illustrates that testing nonequilibrium dynamics can provide new insights into the drivers of colonization, extinction, and diversity fluctuations in metacommunities.

Stress before extinction learning enhances and generalizes extinction memory in a predictive learning task.

Science.gov (United States)

Meir Drexler, Shira; Hamacher-Dang, Tanja C; Wolf, Oliver T

2017-05-01

In extinction learning, the individual learns that a previously acquired association (e.g. between a threat and its predictor) is no longer valid. This learning is the principle underlying many cognitive-behavioral psychotherapeutic treatments, e.g. 'exposure therapy'. However, extinction is often highly-context dependent, leading to renewal (relapse of extinguished conditioned response following context change). We have previously shown that post-extinction stress leads to a more context-dependent extinction memory in a predictive learning task. Yet as stress prior to learning can impair the integration of contextual cues, here we aim to create a more generalized extinction memory by inducing stress prior to extinction. Forty-nine men and women learned the associations between stimuli and outcomes in a predictive learning task (day 1), extinguished them shortly after an exposure to a stress/control condition (day 2), and were tested for renewal (day 3). No group differences were seen in acquisition and extinction learning, and a renewal effect was present in both groups. However, the groups differed in the strength and context-dependency of the extinction memory. Compared to the control group, the stress group showed an overall reduced recovery of responding to the extinguished stimuli, in particular in the acquisition context. These results, together with our previous findings, demonstrate that the effects of stress exposure on extinction memory depend on its timing. While post-extinction stress makes the memory more context-bound, pre-extinction stress strengthens its consolidation for the acquisition context as well, making it potentially more resistant to relapse. These results have implications for the use of glucocorticoids as extinction-enhancers in exposure therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

Reorganization energy upon charging a single molecule on an insulator measured by atomic force microscopy

Science.gov (United States)

Fatayer, Shadi; Schuler, Bruno; Steurer, Wolfram; Scivetti, Ivan; Repp, Jascha; Gross, Leo; Persson, Mats; Meyer, Gerhard

2018-05-01

Intermolecular single-electron transfer on electrically insulating films is a key process in molecular electronics1-4 and an important example of a redox reaction5,6. Electron-transfer rates in molecular systems depend on a few fundamental parameters, such as interadsorbate distance, temperature and, in particular, the Marcus reorganization energy7. This crucial parameter is the energy gain that results from the distortion of the equilibrium nuclear geometry in the molecule and its environment on charging8,9. The substrate, especially ionic films10, can have an important influence on the reorganization energy11,12. Reorganization energies are measured in electrochemistry13 as well as with optical14,15 and photoemission spectroscopies16,17, but not at the single-molecule limit and nor on insulating surfaces. Atomic force microscopy (AFM), with single-charge sensitivity18-22, atomic-scale spatial resolution20 and operable on insulating films, overcomes these challenges. Here, we investigate redox reactions of single naphthalocyanine (NPc) molecules on multilayered NaCl films. Employing the atomic force microscope as an ultralow current meter allows us to measure the differential conductance related to transitions between two charge states in both directions. Thereby, the reorganization energy of NPc on NaCl is determined as (0.8 ± 0.2) eV, and density functional theory (DFT) calculations provide the atomistic picture of the nuclear relaxations on charging. Our approach presents a route to perform tunnelling spectroscopy of single adsorbates on insulating substrates and provides insight into single-electron intermolecular transport.

Temporal factors in the extinction of fear in inbred mouse strains differing in extinction efficacy.

Science.gov (United States)

MacPherson, Kathryn; Whittle, Nigel; Camp, Marguerite; Gunduz-Cinar, Ozge; Singewald, Nicolas; Holmes, Andrew

2013-07-05

Various neuropsychiatric conditions, including posttraumatic stress disorder (PTSD), are characterized by deficient fear extinction, but individuals differ greatly in risk for these. While there is growing evidence that fear extinction is influenced by certain procedural variables, it is unclear how these influences might vary across individuals and subpopulations. To model individual differences in fear extinction, prior studies identified a strain of inbred mouse, 129S1/SvImJ (S1), which exhibits a profound deficit in fear extinction, as compared to other inbred strains, such as C57BL/6J (B6). Here, we assessed the effects of procedural variables on the impaired extinction phenotype of the S1 strain and, by comparison, the extinction-intact B6 strain. The variables studied were 1) the interval between conditioning and extinction, 2) the interval between cues during extinction training, 3) single-cue exposure before extinction training, and 4) extinction of a second-order conditioned cue. Conducting extinction training soon after ('immediately') conditioning attenuated fear retrieval in S1 mice and impaired extinction in B6 mice. Spacing cue presentations with long inter-trial intervals during extinction training augmented fear in S1 and B6 mice. The effect of spacing was lost with one-trial fear conditioning in B6, but not S1 mice. A single exposure to a conditioned cue before extinction training did not alter extinction retrieval, either in B6 or S1 mice. Both the S1 and B6 strains exhibited robust second-order fear conditioning, in which a cue associated with footshock was sufficient to serve as a conditioned exciter to condition a fear association to a second cue. B6 mice extinguished the fear response to the second-order conditioned cue, but S1 mice failed to do so. These data provide further evidence that fear extinction is strongly influenced by multiple procedural variables and is so in a highly strain-dependent manner. This suggests that the efficacy of

Noradrenergic Modulation of Fear Conditioning and Extinction.

Science.gov (United States)

Giustino, Thomas F; Maren, Stephen

2018-01-01

The locus coeruleus norepinephrine (LC-NE) system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning) the locus coeruleus (LC) promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC) might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC) which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP). Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

Noradrenergic Modulation of Fear Conditioning and Extinction

Directory of Open Access Journals (Sweden)

Thomas F. Giustino

2018-03-01

Full Text Available The locus coeruleus norepinephrine (LC-NE system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning the locus coeruleus (LC promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP. Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

76 FR 71919 - Corporate Reorganizations; Allocation of Basis in “All Cash D” Reorganizations

Science.gov (United States)

2011-11-21

... issuing temporary regulations that provide guidance regarding the determination of the basis of stock or securities in a reorganization where no stock or securities of the issuing corporation is issued and... the share of stock of the issuing corporation to which the basis, if any, of the stock or securities...

Modern examples of extinctions

DEFF Research Database (Denmark)

Lövei, Gabor L

2013-01-01

No species lives forever, and extinction is the ultimate fate of all living species. The fossil record indicates that a recent extinction wave affecting terrestrial vertebrates was parallel with the arrival of modern humans to areas formerly uninhabited by them. These modern instances of extinction...

Inhibition of serotonin transporters disrupts the enhancement of fear memory extinction by 3,4-methylenedioxymethamphetamine (MDMA).

Science.gov (United States)

Young, Matthew B; Norrholm, Seth D; Khoury, Lara M; Jovanovic, Tanja; Rauch, Sheila A M; Reiff, Collin M; Dunlop, Boadie W; Rothbaum, Barbara O; Howell, Leonard L

2017-10-01

3,4-Methylenedioxymethamphetamine (MDMA) persistently improves symptoms of post-traumatic stress disorder (PTSD) when combined with psychotherapy. Studies in rodents suggest that these effects can be attributed to enhancement of fear memory extinction. Therefore, MDMA may improve the effects of exposure-based therapy for PTSD, particularly in treatment-resistant patients. However, given MDMA's broad pharmacological profile, further investigation is warranted before moving to a complex clinical population. We aimed to inform clinical research by providing a translational model of MDMA's effect, and elucidating monoaminergic mechanisms through which MDMA enhances fear extinction. We explored the importance of monoamine transporters targeted by MDMA to fear memory extinction, as measured by reductions in conditioned freezing and fear-potentiated startle (FPS) in mice. Mice were treated with selective inhibitors of individual monoamine transporters prior to combined MDMA treatment and fear extinction training. MDMA enhanced the lasting extinction of FPS. Acute and chronic treatment with a 5-HT transporter (5-HTT) inhibitor blocked MDMA's effect on fear memory extinction. Acute inhibition of dopamine (DA) and norepinephrine (NE) transporters had no effect. 5-HT release alone did not enhance extinction. Blockade of MDMA's effect by 5-HTT inhibition also downregulated 5-HT 2A -mediated behavior, and 5-HT 2A antagonism disrupted MDMA's effect on extinction. We validate enhancement of fear memory extinction by MDMA in a translational behavioral model, and reveal the importance of 5-HTT and 5-HT 2A receptors to this effect. These observations support future clinical research of MDMA as an adjunct to exposure therapy, and provide important pharmacological considerations for clinical use in a population frequently treated with 5-HTT inhibitors.

Predators on private land: broad-scale socioeconomic interactions influence large predator management

Directory of Open Access Journals (Sweden)

Hayley S. Clements

2016-06-01

Full Text Available The proliferation of private land conservation areas (PLCAs is placing increasing pressure on conservation authorities to effectively regulate their ecological management. Many PLCAs depend on tourism for income, and charismatic large mammal species are considered important for attracting international visitors. Broad-scale socioeconomic factors therefore have the potential to drive fine-scale ecological management, creating a systemic scale mismatch that can reduce long-term sustainability in cases where economic and conservation objectives are not perfectly aligned. We assessed the socioeconomic drivers and outcomes of large predator management on 71 PLCAs in South Africa. Owners of PLCAs that are stocking free-roaming large predators identified revenue generation as influencing most or all of their management decisions, and rated profit generation as a more important objective than did the owners of PLCAs that did not stock large predators. Ecotourism revenue increased with increasing lion (Panthera leo density, which created a potential economic incentive for stocking lion at high densities. Despite this potential mismatch between economic and ecological objectives, lion densities were sustainable relative to available prey. Regional-scale policy guidelines for free-roaming lion management were ecologically sound. By contrast, policy guidelines underestimated the area required to sustain cheetah (Acinonyx jubatus, which occurred at unsustainable densities relative to available prey. Evidence of predator overstocking included predator diet supplementation and frequent reintroduction of game. We conclude that effective facilitation of conservation on private land requires consideration of the strong and not necessarily beneficial multiscale socioeconomic factors that influence private land management.

On Inferring Extinction Laws in Z -approximately 6 Quasars as Signatures of Supernova Dust

Science.gov (United States)

Hjorth, Jens; Vreeswijk, Paul M.; Gall, Christa; Watson, Darach

2013-01-01

Unusual extinction curves of high-redshift QSOs have been taken as evidence that dust is primarily produced by supernovae at high redshift. In particular, the 3000 °A Todini-Ferrara-Maiolino kink in the extinction curve of the z = 6.20 SDSS J1048+4637 has been attributed to supernova dust. Here we discuss the challenges in inferring robust extinction curves of high-redshift QSOs and critically assess previous claims of detection of supernova dust. In particular, we address the sensitivity to the choice of intrinsic QSO spectrum, the need for a long wavelength baseline, and the drawbacks in fitting theoretical extinction curves. In a sample of 21 QSOs at z 6 we detect significant ultraviolet extinction using existing broad-band optical, near-infrared, and Spitzer photometry. The median extinction curve is consistent with a Small Magellanic Cloud curve with A1450 0.7 mag and does not exhibit any conspicuous (restframe) 2175 °A or 3000 °A features. For two QSOs, SDSS J1044-0125 at z = 5.78 and SDSS J1030+0524 at z = 6.31, we further present X-shooter spectra covering the wavelength range 0.9-2.5 µm. The resulting non-parametric extinction curves do not exhibit the 3000 °A kink. Finally, in a re-analysis of literature spectra of SDSS J1048+4637, we do not find evidence for a conspicuous kink. We conclude that the existing evidence for a 3000 °A feature is weak and that the overall dust properties at high and low redshift show no significant differences. This, however, does not preclude supernovae from dominating the dust budget at high redshift.

Mirror therapy in lower limb amputees. A look beyond primary motor cortex reorganization

International Nuclear Information System (INIS)

Seidel, S.; Essmeister, M.; Sycha, T.; Auff, E.; Kasprian, G.; Furtner, J.; Schoepf, V.; Prayer, D.

2011-01-01

Phantom pain in upper limb amputees is associated with the extent of reorganization in the primary sensorimotor cortex. Mirror visual feedback therapy has been shown to improve phantom pain. We investigated the extent of cortical reorganization in lower limb amputees and changes in neural activity induced by mirror therapy. Eight lower limb amputees underwent 12 sessions of MVFT and functional magnetic resonance imaging (fMRI) of the brain before the first and after the last MVFT session. FMRI sessions consisted of two runs in which subjects were instructed to perform repetitive movement of the healthy and phantom ankle. Before MVFT, the mean phantom pain intensity was 4.6 ± 3.1 on a visual analog scale and decreased to 1.8 ± 1.7 (p = 0.04). We did not observe a consistent pattern of cortical activation in primary sensorimotor areas during phantom limb movements. Following MVFT, increased activity was obtained in the right orbitofrontal cortex during phantom ankle movements. Comparison of cortical activity during movements of the phantom ankle and the intact ankle showed significantly higher activity in the left inferior frontal cortex (pars triangularis). These results question the known association between phantom pain and primary sensorimotor reorganization and propose reorganizational changes involving multiple cortical areas in lower limb amputees. Finally, reduction of phantom pain after mirror visual feedback therapy was associated with increased prefrontal cortical activity during phantom ankle movements. (orig.)

Experimental evidence of dynamic re-organization of evolving landscapes under changing climatic forcing

Science.gov (United States)

Singh, Arvind; Tejedor, Alejandro; Zaliapin, Ilya; Reinhardt, Liam; Foufoula-Georgiou, Efi

2015-04-01

The aim of this study is to better understand the dynamic re-organization of an evolving landscape under a scenario of changing climatic forcing for improving our knowledge of geomorphic transport laws under transient conditions and developing predictive models of landscape response to external perturbations. Real landscape observations for long-term analysis are limited and to this end a high resolution controlled laboratory experiment was conducted at the St. Anthony Falls laboratory at the University of Minnesota. Elevation data were collected at temporal resolution of 5 mins and spatial resolution of 0.5 mm as the landscape approached steady state (constant uplift and precipitation rate) and in the transient state (under the same uplift and 5x precipitation). The results reveal rapid topographic re-organization under a five-fold precipitation increase with the fluvial regime expanding into the previously debris dominated regime, accelerated erosion happening at hillslope scales, and rivers shifting from an erosion-limited to a transport-limited regime. From a connectivity and clustering analysis of the erosional and depositional events, we demonstrate the strikingly different spatial patterns of landscape evolution under steady-state (SS) and transient-state (TS), even when the time under SS is "stretched" compared to that under TS such as to match the total volume and PDF of erosional and depositional amounts. We quantify the spatial coupling of hillslopes and channels and demonstrate that hillslopes lead and channels follow in re-organizing the whole landscape under such an amplified precipitation regime.

A phantom extinction? New insights into extinction dynamics of the Don-hare Lepus tanaiticus.

Science.gov (United States)

Prost, S; Knapp, M; Flemmig, J; Hufthammer, A K; Kosintsev, P; Stiller, M; Hofreiter, M

2010-09-01

The Pleistocene to Holocene transition was accompanied by a worldwide extinction event affecting numerous mammalian species. Several species such as the woolly mammoth and the giant deer survived this extinction wave, only to go extinct a few thousand years later during the Holocene. Another example for such a Holocene extinction is the Don-hare, Lepus tanaiticus, which inhabited the Russian plains during the late glacial. After being slowly replaced by the extant mountain hare (Lepus timidus), it eventually went extinct during the middle Holocene. Here, we report the phylogenetic relationship of L. tanaiticus and L. timidus based on a 339-basepair (bp) fragment of the mitochondrial D-loop. Phylogenetic tree- and network reconstructions do not support L. tanaiticus and L. timidus being different species. Rather, we suggest that the two taxa represent different morphotypes of a single species and the extinction of 'L. tanaiticus' represents the disappearance of a local morphotype rather than the extinction of a species.

Grading Gradients: Evaluating Evidence for Time-dependent Memory Reorganization in Experimental Animals

Directory of Open Access Journals (Sweden)

Katherine G. Akers

2009-01-01

Full Text Available In humans, hippocampal damage typically produces temporally graded retrograde amnesia, with relative sparing of remote memories compared to recent memories. This observation led to the idea that as memories age, they are reorganized in a time-dependent manner. Here, we evaluate evidence for time-dependent memory reorganization in animal models. We conclude that, although hippocampal lesions may not always produce temporal gradients under all conditions, studies using alternate experimental approaches consistently support the idea that memories reorganize over time—becoming less dependent on the hippocampus and more dependent on a cortical network. We further speculate on the processes that drive memory reorganization such as sleep, memory reactivation, synaptic plasticity, and neurogenesis.

The Case for the Younger Dryas Extraterrestrial Impact Event: Mammoth, Megafauna and Clovis Extinction

International Nuclear Information System (INIS)

Firestone, Richard B.

2009-01-01

The onset of >1000 years of Younger Dryas cooling, broad-scale extinctions, and the disappearance of the Clovis culture in North America simultaneously occurred 12,900 years ago followed immediately by the appearance of a carbon-rich black layer at many locations. In situ bones of extinct megafauna and Clovis tools occur only beneath this black layer and not within or above it. At the base of the black mat at 9 Clovis-age sites in North America and a site in Belgium numerous extraterrestrial impact markers were found including magnetic grains highly enriched in iridium, magnetic microspherules, vesicular carbon spherules enriched in cubic, hexagonal, and n-type nanodiamonds, glass-like carbon containing Fullerenes and nanodiamonds, charcoal, soot, and polycyclic aromatic hydrocarbons. The same impact markers were found mixed throughout the sediments of 15 Carolina Bays, elliptical depressions along the Atlantic coast, whose parallel major axes point towards either the Great Lakes or Hudson Bay. The magnetic grains and spherules have an unusual Fe/Ti composition similar to lunar Procellarum KREEP Terrane and the organic constituents are enriched in 14C leading to radiocarbon dates often well into the future. These characteristics are inconsistent with known meteorites and suggest that the impact was by a previous unobserved, possibly extrasolar body. The concentration of impact markers peaks near the Great Lakes and their unusually high water content suggests that a 4.6 km-wide comet fragmented and exploded over the Laurentide Ice Sheet creating numerous craters that now persist at the bottom of the Great Lakes. The coincidence of this impact, the onset of Younger Dryas cooling, extinction of the megafauna, and the appearance of a black mat strongly suggests that all these events are directly related. These results have unleashed an avalanche of controversy which I will address in this paper.

LIFTING THE DUSTY VEIL WITH NEAR- AND MID-INFRARED PHOTOMETRY. II. A LARGE-SCALE STUDY OF THE GALACTIC INFRARED EXTINCTION LAW

International Nuclear Information System (INIS)

Zasowski, G.; Majewski, S. R.; Indebetouw, R.

2009-01-01

We combine near-infrared (Two Micron All Sky Survey) and mid-infrared (Spitzer-IRAC) photometry to characterize the IR extinction law (1.2-8 μm) over nearly 150 deg. of contiguous Milky Way midplane longitude. The relative extinctions in five passbands across these wavelength and longitude ranges are derived by calculating color excess ratios for G and K giant red clump stars in contiguous midplane regions and deriving the wavelength dependence of extinction in each one. Strong, monotonic variations in the extinction law shape are found as a function of angle from the Galactic center, symmetric on either side of it. These longitudinal variations persist even when dense interstellar regions, known a priori to have a shallower extinction curve, are removed. The increasingly steep extinction curves toward the outer Galaxy indicate a steady decrease in the absolute-to-selective extinction ratio (R V ) and in the mean dust grain size at greater Galactocentric angles. We note an increasing strength of the 8 μm extinction inflection at high Galactocentric angles and, using theoretical dust models, show that this behavior is consistent with the trend in R V . Along several lines of sight where the solution is most feasible, A λ /A K s as a function of Galactic radius (R GC ) is estimated and shown to have a Galactic radial dependence. Our analyses suggest that the observed relationship between extinction curve shape and Galactic longitude is due to an intrinsic dependence of the extinction law on Galactocentric radius.

The Late Ordovician Extinction: How it became the best understood of the five major extinctions.

Science.gov (United States)

Sheehan, P.

2003-04-01

The end Ordovician extinction has become arguably the best-understood major extinction event in Earth History. A plethora of workers have established the pattern of faunal change and causes of the extinction with remarkably little disagreement. The first indication of increased extinction at the end of the Ordovician was a graph of global diversity patterns by Norman Newell in 1967, although he did not recognize it as a major event. The presence of a major extinction event became clear as William Berry and Art Boucot assembled data for Silurian correlation charts in the late 1960s. The first reports of North African glaciation in the late 1960s provided a cause for the extinction and study of the event snowballed. It was no accident that recognition of the extinction began in North America, because it was there that the extinction completely overturned faunas in the epicontinental seas. Glacio-eustatic regression of shallow seaway coincided with the disappearance of endemic Laurentian faunas and replacement by a highly cosmopolitan fauna in the Silurian. Once the event was established in North America, paleontologists soon found evidence of the event around the globe. The well-documented Hirnantia Fauna was found to correspond to the glacial interval, and Pat Brenchley soon recognized that there were two pulses of extinction, at the beginning and end of the glaciation. At the same time that the faunal changes were being documented geologic studies of the glaciation provided information on the environmental changes associated with the extinction. The timing of the glacial maximum was established in Africa and by the presence of dropstones in high latitude marine rocks. The 1990s saw geochemical techniques employed that allowed examination of atmospheric CO2 and temperature changes. In many places carbonate deposition declined. Glacio-eustatic regression was obvious in many areas, and a sea-level decline in the range of 50-100 m was established. Shallow

Activation of D1/5 Dopamine Receptors: A Common Mechanism for Enhancing Extinction of Fear and Reward-Seeking Behaviors.

Science.gov (United States)

Abraham, Antony D; Neve, Kim A; Lattal, K Matthew

2016-07-01

Dopamine is critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine's function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in appetitive tasks. A parallel and growing literature indicates that dopamine signaling is involved in consolidation of memories into stable representations in aversive tasks such as fear conditioning. Relatively little is known about how dopamine may modulate memories that form during extinction, when organisms learn that the relation between previously associated events is severed. We investigated whether fear and reward extinction share common mechanisms that could be enhanced with dopamine D1/5 receptor activation. Pharmacological activation of dopamine D1/5 receptors (with SKF 81297) enhanced extinction of both cued and contextual fear. These effects also occurred in the extinction of cocaine-induced conditioned place preference, suggesting that the observed effects on extinction were not specific to a particular type of procedure (aversive or appetitive). A cAMP/PKA biased D1 agonist (SKF 83959) did not affect fear extinction, whereas a broadly efficacious D1 agonist (SKF 83822) promoted fear extinction. Together, these findings show that dopamine D1/5 receptor activation is a target for the enhancement of fear or reward extinction.

Modelling interstellar extinction: Pt. 1

International Nuclear Information System (INIS)

Jones, A.P.

1988-01-01

Several methods of calculating the extinction of porous silicate grains are discussed, these include effective medium theories and hollow spherical shells. Porous silicate grains are shown to produce enhanced infrared, ultraviolet and far-ultraviolet extinction and this effect can be used to reduce the abundance of carbon required to match the average interstellar extinction, however, matching the visual extinction is rather more problematical. We have shown that the enhanced extinction at long and short wavelengths have different origins, and have explained why the visual extinction is little affected by porosity. The implications of porous grains in the interstellar medium are discussed with particular reference to surface chemistry, the polarization of starlight, and their dynamical evolution. (author)

Pollinator declines. Extinctions of aculeate pollinators in Britain and the role of large-scale agricultural changes.

Science.gov (United States)

Ollerton, Jeff; Erenler, Hilary; Edwards, Mike; Crockett, Robin

2014-12-12

Pollinators are fundamental to maintaining both biodiversity and agricultural productivity, but habitat destruction, loss of flower resources, and increased use of pesticides are causing declines in their abundance and diversity. Using historical records, we assessed the rate of extinction of bee and flower-visiting wasp species in Britain from the mid-19th century to the present. The most rapid phase of extinction appears to be related to changes in agricultural policy and practice beginning in the 1920s, before the agricultural intensification prompted by the Second World War, often cited as the most important driver of biodiversity loss in Britain. Slowing of the extinction rate from the 1960s onward may be due to prior loss of the most sensitive species and/or effective conservation programs. Copyright © 2014, American Association for the Advancement of Science.

Designed azurins show lower reorganization free energies for intraprotein electron transfer

DEFF Research Database (Denmark)

Farver, Ole; Marshall, Nicholas M; Wherland, Scot

2013-01-01

Low reorganization free energies are necessary for fast electron transfer (ET) reactions. Hence, rational design of redox proteins with lower reorganization free energies has been a long-standing challenge, promising to yield a deeper understanding of the underlying principles of ET reactivity...

26 CFR 54.4980B-9 - Business reorganizations and employer withdrawals from multiemployer plans.

Science.gov (United States)

2010-04-01

...-9 Business reorganizations and employer withdrawals from multiemployer plans. The following... multiemployer plans: Q-1: For purposes of this section, what are a business reorganization, a stock sale, and an... 26 Internal Revenue 17 2010-04-01 2010-04-01 false Business reorganizations and employer...

Achieving highly efficient and broad-angle polarization beam filtering using epsilon-near-zero metamaterials mimicked by metal-dielectric multilayers

Science.gov (United States)

Wu, Feng

2018-03-01

We report a highly efficient and broad-angle polarization beam filter at visible wavelengths using an anisotropic epsilon-near-zero metamaterial mimicked by a multilayer composed of alternative subwavelength magnesium fluoride and silver layers. The underlying physics can be explained by the dramatic difference between two orthogonal polarizations' iso-frequency curves of anisotropic epsilon-near-zero metamaterials. Transmittance for two orthogonal polarization waves and the polarization extinction ratio are calculated via the transfer matrix method to assess the comprehensive performance of the proposed polarization beam filter. From the simulation results, the proposed polarization beam filter is highly efficient (the polarization extinction ratio is far larger than two orders of magnitude) and has a broad operating angle range (ranging from 30° to 75°). Finally, we show that the proper tailoring of the periodic number enables us to obtain high comprehensive performance of the proposed polarization beam filter.

Extinction Events Can Accelerate Evolution

DEFF Research Database (Denmark)

Lehman, Joel; Miikkulainen, Risto

2015-01-01

Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate...... evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending...... computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific...

INTERACTION BETWEEN MODELS OF THE LIFE CYCLE OF INDUSTRIAL ENTERPRISE AND CYCLE OF ITS REORGANIZATION

Directory of Open Access Journals (Sweden)

Chulkov Vitaliy Olegovich

2012-10-01

Full Text Available The objective of this scientific research is to develop a theoretical model of organizational and technology-related processes of reorganization of industrial enterprises, as well as their interaction. Multipoint logic notions of growth and interaction phases are used as research methods. The author describes the basic stages of reorganization, the life cycle of industrial enterprises and the cycle of their transformation. The processes are presented as an infographical image that represents a concentric model of interaction. This concentric model represents interaction between two or more phases. The process is entitled infografical modeling on the polyfunctional level. The concentric model moves both clockwise and anti-clockwise. Basic organizational and technological processes of reorganization of industrial enterprises that include decision making in terms of expediency of reorganization, design, construction, and performance of industrial enterprises at full capacity, and further operation of the industrial enterprise are described in the paper. Attainment of this objective, namely, reorganization of an industrial enterprise, involves a huge amount of resources, including labour resources that need interaction with all parties of reorganization; therefore, the concentric model of interaction describing the basic cycle of reorganization, the life cycle of an industrial enterprise and the cycle of its conversion is a trustworthy representation of this process. The proposed concentric model of interaction should be used in the design of organizational and technology-related processes for integrated consideration of reorganization of enterprises required to understand and improve the efficiency of reorganizations and to control the reorganization of industrial facilities.

Extinction in neutrally stable stochastic Lotka-Volterra models

Science.gov (United States)

Dobrinevski, Alexander; Frey, Erwin

2012-05-01

Populations of competing biological species exhibit a fascinating interplay between the nonlinear dynamics of evolutionary selection forces and random fluctuations arising from the stochastic nature of the interactions. The processes leading to extinction of species, whose understanding is a key component in the study of evolution and biodiversity, are influenced by both of these factors. Here, we investigate a class of stochastic population dynamics models based on generalized Lotka-Volterra systems. In the case of neutral stability of the underlying deterministic model, the impact of intrinsic noise on the survival of species is dramatic: It destroys coexistence of interacting species on a time scale proportional to the population size. We introduce a new method based on stochastic averaging which allows one to understand this extinction process quantitatively by reduction to a lower-dimensional effective dynamics. This is performed analytically for two highly symmetrical models and can be generalized numerically to more complex situations. The extinction probability distributions and other quantities of interest we obtain show excellent agreement with simulations.

Timing of extinction relative to acquisition: A parametric analysis of fear extinction in humans

NARCIS (Netherlands)

Norrholm, S.D.; Vervliet, B.; Jovanovic, T.; Boshoven, W.; Myers, K.M.; Davis, M.; Rothbaum, B.O.; Duncan, E.J.

2008-01-01

Fear extinction is a reduction in conditioned fear following repeated exposure to the feared cue in the absence of any aversive event. Extinguished fear often reappears after extinction through spontaneous recovery. Animal studies suggest that spontaneous recovery can be abolished if extinction

Mapping of the extinction in Giant Molecular Clouds using optical star counts

OpenAIRE

Cambresy, L.

1999-01-01

This paper presents large scale extinction maps of most nearby Giant Molecular Clouds of the Galaxy (Lupus, rho-Ophiuchus, Scorpius, Coalsack, Taurus, Chamaeleon, Musca, Corona Australis, Serpens, IC 5146, Vela, Orion, Monoceros R1 and R2, Rosette, Carina) derived from a star count method using an adaptive grid and a wavelet decomposition applied to the optical data provided by the USNO-Precision Measuring Machine. The distribution of the extinction in the clouds leads to estimate their total...

Rescaling of temporal expectations during extinction

Science.gov (United States)

Drew, Michael R.; Walsh, Carolyn; Balsam, Peter D

2016-01-01

Previous research suggests that extinction learning is temporally specific. Changing the CS duration between training and extinction can facilitate the loss of the CR within the extinction session but impairs long-term retention of extinction. In two experiments using conditioned magazine approach with rats, we examined the relation between temporal specificity of extinction and CR timing. In Experiment 1 rats were trained on a 12-s, fixed CS-US interval and then extinguished with CS presentations that were 6, 12, or 24 s in duration. The design of Experiment 2 was the same except rats were trained using partial rather than continuous reinforcement. In both experiments, extending the CS duration in extinction facilitated the diminution of CRs during the extinction session, but shortening the CS duration failed to slow extinction. In addition, extending (but not shortening) the CS duration caused temporal rescaling of the CR, in that the peak CR rate migrated later into the trial over the course of extinction training. This migration partially accounted for the faster loss of the CR when the CS duration was extended. Results are incompatible with the hypothesis that extinction is driven by cumulative CS exposure and suggest that temporally extended nonreinforced CS exposure reduces conditioned responding via temporal displacement rather than through extinction per se. PMID:28045291

Dynamic functional reorganizations and relationship with working memory performance in healthy aging.

Directory of Open Access Journals (Sweden)

Roser eSala-Llonch

2012-06-01

Full Text Available In recent years, several theories have been proposed in attempts to identify the neural mechanisms underlying successful cognitive aging. Old subjects show increased neural activity during the performance of tasks, mainly in prefrontal areas, which is interpreted as a compensatory mechanism linked to functional brain efficiency. Moreover, resting-state studies have concluded that elders show disconnection or disruption of large-scale functional networks. We used functional MRI during resting-state and a verbal n-back task with different levels of memory load in a cohort of young and old healthy adults to identify patterns of networks associated with working memory and brain default mode. We found that the disruption of resting-state networks in the elderly coexists with task-related overactivations of certain brain areas and with reorganizations within these functional networks. Moreover, elders who were able to activate additional areas and to recruit a more bilateral frontal pattern within the task-related network achieved successful performance on the task. We concluded that the balanced and plastic reorganization of brain networks underlies successful cognitive aging. This observation allows the integration of several theories that have been proposed to date regarding the aging brain.

End Ordovician extinctions

DEFF Research Database (Denmark)

Harper, David A. T.; Hammarlund, Emma; Rasmussen, Christian M. Ø.

2014-01-01

-global anoxia associated with a marked transgression during the Late Hirnantian. Most recently, however, new drivers for the extinctions have been proposed, including widespread euxinia together with habitat destruction caused by plate tectonic movements, suggesting that the end Ordovician mass extinctions were...

Continuous wave power scaling in high power broad area quantum cascade lasers

Science.gov (United States)

Suttinger, M.; Leshin, J.; Go, R.; Figueiredo, P.; Shu, H.; Lyakh, A.

2018-02-01

Experimental and model results for high power broad area quantum cascade lasers are presented. Continuous wave power scaling from 1.62 W to 2.34 W has been experimentally demonstrated for 3.15 mm-long, high reflection-coated 5.6 μm quantum cascade lasers with 15 stage active region for active region width increased from 10 μm to 20 μm. A semi-empirical model for broad area devices operating in continuous wave mode is presented. The model uses measured pulsed transparency current, injection efficiency, waveguide losses, and differential gain as input parameters. It also takes into account active region self-heating and sub-linearity of pulsed power vs current laser characteristic. The model predicts that an 11% improvement in maximum CW power and increased wall plug efficiency can be achieved from 3.15 mm x 25 μm devices with 21 stages of the same design but half doping in the active region. For a 16-stage design with a reduced stage thickness of 300Å, pulsed roll-over current density of 6 kA/cm2 , and InGaAs waveguide layers; optical power increase of 41% is projected. Finally, the model projects that power level can be increased to 4.5 W from 3.15 mm × 31 μm devices with the baseline configuration with T0 increased from 140 K for the present design to 250 K.

Extinction of NGC 7027

International Nuclear Information System (INIS)

Seaton, M.J.

1979-01-01

Emission intensities of recombination lines in hydrogenic spectra are known accurately relative to intensities in the free-free radio continuum. For NGC 7027 intensities have been measured for the radio continuum and for H I and He II lines in the wavelength range from lambda = 2.17 μm to lambda = 1640 A: comparison with the calculated emission intensities gives the extinction. Determinations of the standard interstellar extinction function are critically discussed. The extinction deduced for the total radiation from NGC 7027 has a dependence on wavelength for 6563 A >= lambda >= 1640 A which is in excellent agreement with the adopted standard results, but there are some anomalies for longer wavelengths and for the ratio of total to selective extinction. These can be explained using a model which allows for a local contribution to the extinction which is variable over the surface of the nebula. (author)

Elemental conservation units: communicating extinction risk without dictating targets for protection.

Science.gov (United States)

Wood, Chris C; Gross, Mart R

2008-02-01

Conservation biologists mostly agree on the need to identify and protect biodiversity below the species level but have not yet resolved the best approach. We addressed 2 issues relevant to this debate. First, we distinguished between the abstract goal of preserving the maximum amount of unique biodiversity and the pragmatic goal of minimizing the loss of ecological goods and services given that further loss of biodiversity seems inevitable. Second, we distinguished between the scientific task of assessing extinction risk and the normative task of choosing targets for protection. We propose that scientific advice on extinction risk be given at the smallest meaningful scale: the elemental conservation unit (ECU). An ECU is a demographically isolated population whose probability of extinction over the time scale of interest (say 100 years) is not substantially affected by natural immigration from other populations. Within this time frame, the loss of an ECU would be irreversible without human intervention. Society's decision to protect an ECU ought to reflect human values that have social, economic, and political dimensions. Scientists can best inform this decision by providing advice about the probability that an ECU will be lost and the ecological and evolutionary consequences of that loss in a form that can be integrated into landscape planning. The ECU approach provides maximum flexibility to decision makers and ensures that the scientific task of assessing extinction risk informs, but remains distinct from, the normative social challenge of setting conservation targets.

The role of cooperation and parasites in non-linear replicator delayed extinctions

International Nuclear Information System (INIS)

Sardanyes, Josep; Sole, Ricard V.

2007-01-01

In the present work we study the role of cooperation and parasites on extinction delayed transitions for self-replicating species with catalytic activity. We first use a one-dimensional continuous equation to study the dynamics of both single autocatalytic replicator and symmetric two-member hypercycles, where two well-defined phases involving survival and extinction of replicators are shown to exist. Extinction dynamics is analyzed numerically and analytically and under both deterministic and stochastic scenarios. A ghost is also found for the single autocatalytic replicator and for the asymmetric hypercycle, with an extinction time delay following the square-root scaling law near bifurcation threshold. We find that the extinction delay is longer for the two-member hypercycle than for the single autocatalytic species, indicating that cooperation among replicators might involve to spend a longer time in the bottle-neck region of the ghost. The asymmetry of the network is shown to prolong the extinction time. We also show that an attached parasite decreases the time spent in the bottle-neck region of the ghost, thus accelerating extinction in these systems of replicators. Nevertheless the effect of the parasite is not so important when replicators catalytically cooperate, being the two-member hypercycle less sensitive to the parasite than the autocatalytic species. Here the hypercycle asymmetry can also significantly increase the delaying capacity. These features make the hypercycle to undergo a longer extinction delay, thus increasing the memory effect of the ghost. We finally explore the role of the ghost in fluctuating media, where the extinction delayed transition is shown to increase the survival probability of cooperating catalytic species

Extinction with multiple excitors

OpenAIRE

McConnell, Bridget L.; Miguez, Gonzalo; Miller, Ralph R.

2013-01-01

Four conditioned suppression experiments with rats, using an ABC renewal design, investigated the effects of compounding the target conditioned excitor with additional, nontarget conditioned excitors during extinction. Experiment 1 showed stronger extinction, as evidenced by less renewal, when the target excitor was extinguished in compound with a second excitor, relative to when it was extinguished with associatively neutral stimuli. Critically, this deepened extinction effect was attenuated...

Relict or colonizer? Extinction and range expansion of penguins in southern New Zealand

Science.gov (United States)

Boessenkool, Sanne; Austin, Jeremy J.; Worthy, Trevor H.; Scofield, Paul; Cooper, Alan; Seddon, Philip J.; Waters, Jonathan M.

2008-01-01

Recent human expansion into the Pacific initiated a dramatic avian extinction crisis, and surviving taxa are typically interpreted as declining remnants of previously abundant populations. As a case in point, New Zealand's endangered yellow-eyed penguin (Megadyptes antipodes) is widely considered to have been more abundant and widespread in the past. By contrast, our genetic and morphological analyses of prehistoric, historic and modern penguin samples reveal that this species expanded its range to the New Zealand mainland only in the last few hundred years. This range expansion was apparently facilitated by the extinction of M. antipodes' previously unrecognized sister species following Polynesian settlement in New Zealand. Based on combined genetic and morphological data, we describe this new penguin species, the first known to have suffered human-mediated extinction. The range expansion of M. antipodes so soon after the extinction of its sister species supports a historic paradigmatic shift in New Zealand Polynesian culture. Additionally, such a dynamic biological response to human predation reveals a surprising and less recognized potential for species to have benefited from the extinction of their ecologically similar sister taxa and highlights the complexity of large-scale extinction events. PMID:19019791

Extinction transition in stochastic population dynamics in a random, convective environment

International Nuclear Information System (INIS)

Juhász, Róbert

2013-01-01

Motivated by modeling the dynamics of a population living in a flowing medium where the environmental factors are random in space, we have studied an asymmetric variant of the one-dimensional contact process, where the quenched random reproduction rates are systematically greater in one direction than in the opposite one. The spatial disorder turns out to be a relevant perturbation but, according to results of Monte Carlo simulations, the behavior of the model at the extinction transition is different from the (infinite-randomness) critical behavior of the disordered symmetric contact process. Depending on the strength a of the asymmetry, the critical population drifts either with a finite velocity or with an asymptotically vanishing velocity as x(t) ∼ t μ(a) , where μ(a) < 1. Dynamical quantities are non-self-averaging at the extinction transition; the survival probability, for instance, shows multiscaling, i.e. it is characterized by a broad spectrum of effective exponents. For a sufficiently weak asymmetry, a Griffiths phase appears below the extinction transition, where the survival probability decays as a non-universal power of the time while, above the transition, another extended phase emerges, where the front of the population advances anomalously with a diffusion exponent continuously varying with the control parameter. (paper)

Lesion characteristics driving right-hemispheric language reorganization in congenital left-hemispheric brain damage.

Science.gov (United States)

Lidzba, Karen; de Haan, Bianca; Wilke, Marko; Krägeloh-Mann, Ingeborg; Staudt, Martin

2017-10-01

Pre- or perinatally acquired ("congenital") left-hemispheric brain lesions can be compensated for by reorganizing language into homotopic brain regions in the right hemisphere. Language comprehension may be hemispherically dissociated from language production. We investigated the lesion characteristics driving inter-hemispheric reorganization of language comprehension and language production in 19 patients (7-32years; eight females) with congenital left-hemispheric brain lesions (periventricular lesions [n=11] and middle cerebral artery infarctions [n=8]) by fMRI. 16/17 patients demonstrated reorganized language production, while 7/19 patients had reorganized language comprehension. Lesions to the insular cortex and the temporo-parietal junction (predominantly supramarginal gyrus) were significantly more common in patients in whom both, language production and comprehension were reorganized. These areas belong to the dorsal stream of the language network, participating in the auditory-motor integration of language. Our data suggest that the integrity of this stream might be crucial for a normal left-lateralized language development. Copyright © 2017. Published by Elsevier Inc.

Is IR going extinct?

Science.gov (United States)

Mitchell, Audra

2016-01-01

A global extinction crisis may threaten the survival of most existing life forms. Influential discourses of ‘existential risk’ suggest that human extinction is a real possibility, while several decades of evidence from conservation biology suggests that the Earth may be entering a ‘sixth mass extinction event’. These conditions threaten the possibilities of survival and security that are central to most branches of International Relations. However, this discipline lacks a framework for addressing (mass) extinction. From notions of ‘nuclear winter’ and ‘omnicide’ to contemporary discourses on catastrophe, International Relations thinking has treated extinction as a superlative of death. This is a profound category mistake: extinction needs to be understood not in the ontic terms of life and death, but rather in the ontological context of be(com)ing and negation. Drawing on the work of theorists of the ‘inhuman’ such as Quentin Meillassoux, Claire Colebrook, Ray Brassier, Jean-Francois Lyotard and Nigel Clark, this article provides a pathway for thinking beyond existing horizons of survival and imagines a profound transformation of International Relations. Specifically, it outlines a mode of cosmopolitics that responds to the element of the inhuman and the forces of extinction. Rather than capitulating to narratives of tragedy, this cosmopolitics would make it possible to think beyond the restrictions of existing norms of ‘humanity’ to embrace an ethics of gratitude and to welcome the possibility of new worlds, even in the face of finitude.

Methyl CpG–binding proteins induce large-scale chromatin reorganization during terminal differentiation

Science.gov (United States)

Brero, Alessandro; Easwaran, Hariharan P.; Nowak, Danny; Grunewald, Ingrid; Cremer, Thomas; Leonhardt, Heinrich; Cardoso, M. Cristina

2005-01-01

Pericentric heterochromatin plays an important role in epigenetic gene regulation. We show that pericentric heterochromatin aggregates during myogenic differentiation. This clustering leads to the formation of large chromocenters and correlates with increased levels of the methyl CpG–binding protein MeCP2 and pericentric DNA methylation. Ectopic expression of fluorescently tagged MeCP2 mimicked this effect, causing a dose-dependent clustering of chromocenters in the absence of differentiation. MeCP2-induced rearrangement of heterochromatin occurred throughout interphase, did not depend on the H3K9 histone methylation pathway, and required the methyl CpG–binding domain (MBD) only. Similar to MeCP2, another methyl CpG–binding protein, MBD2, also increased during myogenic differentiation and could induce clustering of pericentric regions, arguing for functional redundancy. This MeCP2- and MBD2-mediated chromatin reorganization may thus represent a molecular link between nuclear genome topology and the epigenetic maintenance of cellular differentiation. PMID:15939760

Endocranial Morphology of the Extinct North American Lion (Panthera atrox).

Science.gov (United States)

Cuff, Andrew R; Stockey, Christopher; Goswami, Anjali

2016-01-01

The extinct North American lion (Panthera atrox) is one of the largest felids (Mammalia, Carnivora) to have ever lived, and it is known from a plethora of incredibly well-preserved remains. Despite this abundance of material, there has been little research into its endocranial anatomy. CT scans of a skull of P. atrox from the Pleistocene La Brea Tar pits were used to generate the first virtual endocranium for this species and to elucidate previously unknown details of its brain size and gross structure, cranial nerves, and inner-ear morphology. Results show that its gross brain anatomy is broadly similar to that of other pantherines, although P. atrox displays less cephalic flexure than either extant lions or tigers, instead showing a brain shape that is reminiscent of earlier felids. Despite this unusual reduction in flexure, the estimated absolute brain size for this specimen is one of the largest reported for any felid, living or extinct. Its encephalization quotient (brain size as a fraction of the expected brain mass for a given body mass) is also larger than that of extant lions but similar to that of the other pantherines. The advent of CT scans has allowed nondestructive sampling of anatomy that cannot otherwise be studied in these extinct lions, leading to a more accurate reconstruction of endocranial morphology and its evolution. © 2017 S. Karger AG, Basel.

Global warming and extinctions of endemic species from biodiversity hotspots.

Science.gov (United States)

Malcolm, Jay R; Liu, Canran; Neilson, Ronald P; Hansen, Lara; Hannah, Lee

2006-04-01

Global warming is a key threat to biodiversity, but few researchers have assessed the magnitude of this threat at the global scale. We used major vegetation types (biomes) as proxies for natural habitats and, based on projected future biome distributions under doubled-CO2 climates, calculated changes in habitat areas and associated extinctions of endemic plant and vertebrate species in biodiversity hotspots. Because of numerous uncertainties in this approach, we undertook a sensitivity analysis of multiple factors that included (1) two global vegetation models, (2) different numbers of biome classes in our biome classification schemes, (3) different assumptions about whether species distributions were biome specific or not, and (4) different migration capabilities. Extinctions were calculated using both species-area and endemic-area relationships. In addition, average required migration rates were calculated for each hotspot assuming a doubled-CO2 climate in 100 years. Projected percent extinctions ranged from hotspots were the Cape Floristic Region, Caribbean, Indo-Burma, Mediterranean Basin, Southwest Australia, and Tropical Andes, where plant extinctions per hotspot sometimes exceeded 2000 species. Under the assumption that projected habitat changes were attained in 100 years, estimated global-warming-induced rates of species extinctions in tropical hotspots in some cases exceeded those due to deforestation, supporting suggestions that global warming is one of the most serious threats to the planet's biodiversity.

Auditory cross-modal reorganization in cochlear implant users indicates audio-visual integration.

Science.gov (United States)

Stropahl, Maren; Debener, Stefan

2017-01-01

There is clear evidence for cross-modal cortical reorganization in the auditory system of post-lingually deafened cochlear implant (CI) users. A recent report suggests that moderate sensori-neural hearing loss is already sufficient to initiate corresponding cortical changes. To what extend these changes are deprivation-induced or related to sensory recovery is still debated. Moreover, the influence of cross-modal reorganization on CI benefit is also still unclear. While reorganization during deafness may impede speech recovery, reorganization also has beneficial influences on face recognition and lip-reading. As CI users were observed to show differences in multisensory integration, the question arises if cross-modal reorganization is related to audio-visual integration skills. The current electroencephalography study investigated cortical reorganization in experienced post-lingually deafened CI users ( n  = 18), untreated mild to moderately hearing impaired individuals (n = 18) and normal hearing controls ( n  = 17). Cross-modal activation of the auditory cortex by means of EEG source localization in response to human faces and audio-visual integration, quantified with the McGurk illusion, were measured. CI users revealed stronger cross-modal activations compared to age-matched normal hearing individuals. Furthermore, CI users showed a relationship between cross-modal activation and audio-visual integration strength. This may further support a beneficial relationship between cross-modal activation and daily-life communication skills that may not be fully captured by laboratory-based speech perception tests. Interestingly, hearing impaired individuals showed behavioral and neurophysiological results that were numerically between the other two groups, and they showed a moderate relationship between cross-modal activation and the degree of hearing loss. This further supports the notion that auditory deprivation evokes a reorganization of the auditory system

Auditory cross-modal reorganization in cochlear implant users indicates audio-visual integration

Directory of Open Access Journals (Sweden)

Maren Stropahl

2017-01-01

Full Text Available There is clear evidence for cross-modal cortical reorganization in the auditory system of post-lingually deafened cochlear implant (CI users. A recent report suggests that moderate sensori-neural hearing loss is already sufficient to initiate corresponding cortical changes. To what extend these changes are deprivation-induced or related to sensory recovery is still debated. Moreover, the influence of cross-modal reorganization on CI benefit is also still unclear. While reorganization during deafness may impede speech recovery, reorganization also has beneficial influences on face recognition and lip-reading. As CI users were observed to show differences in multisensory integration, the question arises if cross-modal reorganization is related to audio-visual integration skills. The current electroencephalography study investigated cortical reorganization in experienced post-lingually deafened CI users (n = 18, untreated mild to moderately hearing impaired individuals (n = 18 and normal hearing controls (n = 17. Cross-modal activation of the auditory cortex by means of EEG source localization in response to human faces and audio-visual integration, quantified with the McGurk illusion, were measured. CI users revealed stronger cross-modal activations compared to age-matched normal hearing individuals. Furthermore, CI users showed a relationship between cross-modal activation and audio-visual integration strength. This may further support a beneficial relationship between cross-modal activation and daily-life communication skills that may not be fully captured by laboratory-based speech perception tests. Interestingly, hearing impaired individuals showed behavioral and neurophysiological results that were numerically between the other two groups, and they showed a moderate relationship between cross-modal activation and the degree of hearing loss. This further supports the notion that auditory deprivation evokes a reorganization of the

The currency and tempo of extinction.

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Regan, H M; Lupia, R; Drinnan, A N; Burgman, M A

2001-01-01

This study examines estimates of extinction rates for the current purported biotic crisis and from the fossil record. Studies that compare current and geological extinctions sometimes use metrics that confound different sources of error and reflect different features of extinction processes. The per taxon extinction rate is a standard measure in paleontology that avoids some of the pitfalls of alternative approaches. Extinction rates reported in the conservation literature are rarely accompanied by measures of uncertainty, despite many elements of the calculations being subject to considerable error. We quantify some of the most important sources of uncertainty and carry them through the arithmetic of extinction rate calculations using fuzzy numbers. The results emphasize that estimates of current and future rates rely heavily on assumptions about the tempo of extinction and on extrapolations among taxa. Available data are unlikely to be useful in measuring magnitudes or trends in current extinction rates.

Optimizing resource allocation and patient flow: process analysis and reorganization in three chemotherapy outpatient clinics.

Science.gov (United States)

Holmes, Morgan; Bodie, Kelly; Porter, Geoffrey; Sullivan, Victoria; Tarasuk, Joy; Trembley, Jodie; Trudeau, Maureen

2010-01-01

Optimizing human and physical resources is a major concern for cancer care decision-makers and practitioners. This issue is particularly acute in the context of ambulatory out patient chemotherapy clinics, especially when - as is the case almost everywhere in the industrialized world - the number of people requiring systemic therapy is increasing while budgets, staffing and physical space remain static. Recent initiatives at three hospital-based chemotherapy units - in Halifax, Toronto and Kingston - shed light on the value of process analysis and reorganization for using existing human and physical resources to their full potential, improving patient flow and enhancing patient satisfaction. The steps taken in these settings are broadly applicable to other healthcare settings and would likely result in similar benefits in those environments.

Immediate extinction causes a less durable loss of performance than delayed extinction following either fear or appetitive conditioning

OpenAIRE

Woods, Amanda M.; Bouton, Mark E.

2008-01-01

Five experiments with rat subjects compared the effects of immediate and delayed extinction on the durability of extinction learning. Three experiments examined extinction of fear conditioning (using the conditioned emotional response method), and two experiments examined extinction of appetitive conditioning (using the food-cup entry method). In all experiments, conditioning and extinction were accomplished in single sessions, and retention testing took place 24 h after extinction. In both f...

Attachment reorganization following divorce: normative processes and individual differences.

Science.gov (United States)

Sbarra, David A; Borelli, Jessica L

2018-03-21

This paper uses attachment theory as a lens for reviewing contemporary research on how adults cope with marital separation and loss. The first section of the paper discusses the process of normative attachment reorganization, or the psychology of adaptive grief responses following relationship transitions. We argue that changes two processes, in particular, can be uses to track changes in this normative reorganization process: narrative coherence and self-concept clarity. The second section of the paper suggest that individual differences in attachment anxiety and avoidance shape the variability in this normative reorganization process, largely as a result of the characteristic ways in which these styles organize emotion-regulatory tendencies. The paper closes with a series of integrative questions for future research, including a call for new studies aimed at understanding under what contexts anxiety and avoidance may be adaptive in promoting emotion recovery to separation and divorce experiences. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extinction risk escalates in the tropics.

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Jana C Vamosi

Full Text Available The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction and we discuss mechanisms that may reconcile this apparent contradiction.

Extinction risk escalates in the tropics.

Science.gov (United States)

Vamosi, Jana C; Vamosi, Steven M

2008-01-01

The latitudinal biodiversity gradient remains one of the most widely recognized yet puzzling patterns in nature. Presently, the high level of extinction of tropical species, referred to as the "tropical biodiversity crisis", has the potential to erode this pattern. While the connection between species richness, extinction, and speciation has long intrigued biologists, these interactions have experienced increased poignancy due to their relevancy to where we should concentrate our conservation efforts. Natural extinction is a phenomenon thought to have its own latitudinal gradient, with lower extinction rates in the tropics being reported in beetles, birds, mammals, and bivalves. Processes that have buffered ecosystems from high extinction rates in the past may also buffer ecosystems against disturbance of anthropogenic origin. While potential parallels between historical and present-day extinction patterns have been acknowledged, they remain only superficially explored and plant extinction patterns have been particularly neglected. Studies on the disappearances of animal species have reached conflicting conclusions, with the rate of extinction appearing either higher or lower in species richness hotspots. Our global study of extinction risk in vascular plants finds disproportionately higher extinction risk in tropical countries, even when indicators of human pressure (GDP, population density, forest cover change) are taken into account. Our results are at odds with the notion that the tropics represent a museum of plant biodiversity (places of historically lowered extinction) and we discuss mechanisms that may reconcile this apparent contradiction.

A scenario for impacts of water availability loss due to climate change on riverine fish extinction rates

OpenAIRE

Tedesco, Pablo; Oberdorff, Thierry; Cornu, Jean-François; Beauchard, O.; Brosse, S.; Durr, H. H.; Grenouillet, G.; Leprieur, F.; Tisseuil, Clément; Zaiss, Rainer; Hugueny, Bernard

2013-01-01

1. Current models estimating impact of habitat loss on biodiversity in the face of global climate change usually project only percentages of species committed to extinction' on an uncertain time-scale. Here, we show that this limitation can be overcome using an empirically derived background extinction rate-area' curve to estimate natural rates and project future rates of freshwater fish extinction following variations in river drainage area resulting from global climate change.2. Based on fu...

Rescuing Ecosystems from Extinction Cascades

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Sahasrabudhe, Sagar; Motter, Adilson

2010-03-01

Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

Magnetic resonance imaging research progress on brain functional reorganization after peripheral nerve injury

International Nuclear Information System (INIS)

Wang Weiwei; Liu Hanqiu

2013-01-01

In the recent years, with the development of functional magnetic resonance imaging technology the brain plasticity and functional reorganization are hot topics in the central nervous system imaging studies. Brain functional reorganization and rehabilitation after peripheral nerve injury may have certain regularity. In this paper, the progress of brain functional magnetic resonance imaging technology and its applications in the world wide clinical and experimental researches of the brain functional reorganization after peripheral nerve injury is are reviewed. (authors)

Similar processes but different environmental filters for soil bacterial and fungal community composition turnover on a broad spatial scale.

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Chemidlin Prévost-Bouré, Nicolas; Dequiedt, Samuel; Thioulouse, Jean; Lelièvre, Mélanie; Saby, Nicolas P A; Jolivet, Claudy; Arrouays, Dominique; Plassart, Pierre; Lemanceau, Philippe; Ranjard, Lionel

2014-01-01

Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2): i) to examine their spatial structuring; ii) to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii) to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landescommunities' composition turnovers. The relative importance of processes and filters was assessed by distance-based redundancy analysis. This study demonstrates significant community composition turnover rates for soil bacteria and fungi, which were dependent on the region. Bacterial and fungal community composition turnovers were mainly driven by environmental selection explaining from 10% to 20% of community composition variations, but spatial variables also explained 3% to 9% of total variance. These variables highlighted significant spatial autocorrelation of both communities unexplained by the environmental variables measured and could partly be explained by dispersal limitations. Although the identified filters and their hierarchy were dependent on the region and organism, selection was systematically based on a common group of environmental variables: pH, trophic resources, texture and land use. Spatial autocorrelation was also important at coarse (80 to 120 km radius) and/or medium (40 to 65 km radius) spatial scales, suggesting dispersal limitations at these scales.

Limitations to Plasticity of Language Network Reorganization in Localization Related Epilepsy

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Mbwana, J.; Berl, M. M.; Ritzl, E. K.; Rosenberger, L.; Mayo, J.; Weinstein, S.; Conry, J. A.; Pearl, P. L.; Shamim, S.; Moore, E. N.; Sato, S.; Vezina, L. G.; Theodore, W. H.; Gaillard, W. D.

2009-01-01

Neural networks for processing language often are reorganized in patients with epilepsy. However, the extent and location of within and between hemisphere re-organization are not established. We studied 45 patients, all with a left hemisphere seizure focus (mean age 22.8, seizure onset 13.3), and 19 normal controls (mean age 24.8) with an fMRI…

Stress and Fear Extinction

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Maren, Stephen; Holmes, Andrew

2016-01-01

Stress has a critical role in the development and expression of many psychiatric disorders, and is a defining feature of posttraumatic stress disorder (PTSD). Stress also limits the efficacy of behavioral therapies aimed at limiting pathological fear, such as exposure therapy. Here we examine emerging evidence that stress impairs recovery from trauma by impairing fear extinction, a form of learning thought to underlie the suppression of trauma-related fear memories. We describe the major structural and functional abnormalities in brain regions that are particularly vulnerable to stress, including the amygdala, prefrontal cortex, and hippocampus, which may underlie stress-induced impairments in extinction. We also discuss some of the stress-induced neurochemical and molecular alterations in these brain regions that are associated with extinction deficits, and the potential for targeting these changes to prevent or reverse impaired extinction. A better understanding of the neurobiological basis of stress effects on extinction promises to yield novel approaches to improving therapeutic outcomes for PTSD and other anxiety and trauma-related disorders. PMID:26105142

Temporal specificity of extinction in autoshaping.

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Drew, Michael R; Yang, Cynthia; Ohyama, Tatsuya; Balsam, Peter D

2004-07-01

Three experiments investigated the effects of varying the conditioned stimulus (CS) duration between training and extinction. Ring doves (Streptopelia risoria) were autoshaped on a fixed CS-unconditioned stimulus (US) interval and extinguished with CS presentations that were longer, shorter, or the same as the training duration. During a subsequent test session, the training CS duration was reintroduced. Results suggest that the cessation of responding during an extinction session is controlled by generalization of excitation between the training and extinction CSs and by the number of nonreinforced CS presentations. Transfer of extinction to the training CS is controlled by the similarity between the extinction and training CSs. Extinction learning is temporally specific. (c) 2004 APA, all rights reserved

Tree growth and climate in the Pacific Northwest, North America: a broad-scale analysis of changing growth environments

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Whitney L. Albright; David L. Peterson

2013-01-01

Climate change in the 21st century will affect tree growth in the Pacific Northwest region of North America, although complex climate–growth relationships make it difficult to identify how radial growth will respond across different species distributions. We used a novel method to examine potential growth responses to climate change at a broad geographical scale with a...

Non-exponential extinction of radiation by fractional calculus modelling

International Nuclear Information System (INIS)

Casasanta, G.; Ciani, D.; Garra, R.

2012-01-01

Possible deviations from exponential attenuation of radiation in a random medium have been recently studied in several works. These deviations from the classical Beer-Lambert law were justified from a stochastic point of view by Kostinski (2001) . In his model he introduced the spatial correlation among the random variables, i.e. a space memory. In this note we introduce a different approach, including a memory formalism in the classical Beer-Lambert law through fractional calculus modelling. We find a generalized Beer-Lambert law in which the exponential memoryless extinction is only a special case of non-exponential extinction solutions described by Mittag-Leffler functions. We also justify this result from a stochastic point of view, using the space fractional Poisson process. Moreover, we discuss some concrete advantages of this approach from an experimental point of view, giving an estimate of the deviation from exponential extinction law, varying the optical depth. This is also an interesting model to understand the meaning of fractional derivative as an instrument to transmit randomness of microscopic dynamics to the macroscopic scale.

Ventromedial prefrontal cortex pyramidal cells have a temporal dynamic role in recall and extinction of cocaine-associated memory.

Science.gov (United States)

Van den Oever, Michel C; Rotaru, Diana C; Heinsbroek, Jasper A; Gouwenberg, Yvonne; Deisseroth, Karl; Stuber, Garret D; Mansvelder, Huibert D; Smit, August B

2013-11-13

In addicts, associative memories related to the rewarding effects of drugs of abuse can evoke powerful craving and drug seeking urges, but effective treatment to suppress these memories is not available. Detailed insight into the neural circuitry that mediates expression of drug-associated memory is therefore of crucial importance. Substantial evidence from rodent models of addictive behavior points to the involvement of the ventromedial prefrontal cortex (vmPFC) in conditioned drug seeking, but specific knowledge of the temporal role of vmPFC pyramidal cells is lacking. To this end, we used an optogenetics approach to probe the involvement of vmPFC pyramidal cells in expression of a recent and remote conditioned cocaine memory. In mice, we expressed Channelrhodopsin-2 (ChR2) or Halorhodopsin (eNpHR3.0) in pyramidal cells of the vmPFC and studied the effect of activation or inhibition of these cells during expression of a cocaine-contextual memory on days 1-2 (recent) and ∼3 weeks (remote) after conditioning. Whereas optical activation of pyramidal cells facilitated extinction of remote memory, without affecting recent memory, inhibition of pyramidal cells acutely impaired recall of recent cocaine memory, without affecting recall of remote memory. In addition, we found that silencing pyramidal cells blocked extinction learning at the remote memory time-point. We provide causal evidence of a critical time-dependent switch in the contribution of vmPFC pyramidal cells to recall and extinction of cocaine-associated memory, indicating that the circuitry that controls expression of cocaine memories reorganizes over time.

Thermal Transgressions and Phanerozoic Extinctions

Science.gov (United States)

Worsley, T. R.; Kidder, D. L.

2007-12-01

A number of significant Phanerozoic extinctions are associated with marine transgressions that were probably driven by rapid ocean warming. The conditions associated with what we call thermal transgressions are extremely stressful to life on Earth. The Earth system setting associated with end-Permian extinction exemplifies an end-member case of our model. The conditions favoring extreme warmth and sea-level increases driven by thermal expansion are also conducive to changes in ocean circulation that foster widespread anoxia and sulfidic subsurface ocean waters. Equable climates are characterized by reduced wind shear and weak surface ocean circulation. Late Permian and Early Triassic thermohaline circulation differs considerably from today's world, with minimal polar sinking and intensified mid-latitude sinking that delivers sulfate from shallow evaporative areas to deeper water where it is reduced to sulfide. Reduced nutrient input to oceans from land at many of the extinction intervals results from diminished silicate weathering and weakened delivery of iron via eolian dust. The falloff in iron-bearing dust leads to minimal nitrate production, weakening food webs and rendering faunas and floras more susceptible to extinction when stressed. Factors such as heat, anoxia, ocean acidification, hypercapnia, and hydrogen sulfide poisoning would significantly affect these biotas. Intervals of tectonic quiescence set up preconditions favoring extinctions. Reductions in chemical silicate weathering lead to carbon dioxide buildup, oxygen drawdown, nutrient depletion, wind and ocean current abatement, long-term global warming, and ocean acidification. The effects of extinction triggers such as large igneous provinces, bolide impacts, and episodes of sudden methane release are more potent against the backdrop of our proposed preconditions. Extinctions that have characteristics we call for in the thermal transgressions include the Early Cambrian Sinsk event, as well as

Wetland characteristics linked to broad-scale patterns in Culiseta melanura abundance and eastern equine encephalitis virus infection.

Science.gov (United States)

Skaff, Nicholas K; Armstrong, Philip M; Andreadis, Theodore G; Cheruvelil, Kendra S

2017-10-18

Eastern equine encephalitis virus (EEEV) is an expanding mosquito-borne threat to humans and domestic animal populations in the northeastern United States. Outbreaks of EEEV are challenging to predict due to spatial and temporal uncertainty in the abundance and viral infection of Cs. melanura, the principal enzootic vector. EEEV activity may be closely linked to wetlands because they provide essential habitat for mosquito vectors and avian reservoir hosts. However, wetlands are not homogeneous and can vary by vegetation, connectivity, size, and inundation patterns. Wetlands may also have different effects on EEEV transmission depending on the assessed spatial scale. We investigated associations between wetland characteristics and Cs. melanura abundance and infection with EEEV at multiple spatial scales in Connecticut, USA. Our findings indicate that wetland vegetative characteristics have strong associations with Cs. melanura abundance. Deciduous and evergreen forested wetlands were associated with higher Cs. melanura abundance, likely because these wetlands provide suitable subterranean habitat for Cs. melanura development. In contrast, Cs. melanura abundance was negatively associated with emergent and scrub/shrub wetlands, and wetland connectivity to streams. These relationships were generally strongest at broad spatial scales. Additionally, the relationships between wetland characteristics and EEEV infection in Cs. melanura were generally weak. However, Cs. melanura abundance was strongly associated with EEEV infection, suggesting that wetland-associated changes in abundance may be indirectly linked to EEEV infection in Cs. melanura. Finally, we found that wet hydrological conditions during the transmission season and during the fall/winter preceding the transmission season were associated with higher Cs. melanura abundance and EEEV infection, indicating that wet conditions are favorable for EEEV transmission. These results expand the broad-scale understanding

Trajectories of Late Permian – Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction

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W. Kiessling

2011-02-01

Full Text Available The hypothesis that ocean acidification was a proximate trigger of the marine end-Triassic mass extinction rests on the assumption that taxa that strongly invest in the secretion of calcium-carbonate skeletons were significantly more affected by the crisis than other taxa. An argument against this hypothesis is the great extinction toll of radiolarians that has been reported from work on local sections. Radiolarians have siliceous tests and thus should be less affected by ocean acidification. We compiled taxonomically vetted occurrences of late Permian and Mesozoic radiolarians and analyzed extinction dynamics of radiolarian genera. Although extinction rates were high at the end of the Triassic, there is no evidence for a mass extinction in radiolarians but rather significantly higher background extinction in the Triassic than in the Jurassic. Although the causes for this decline in background extinction levels remain unclear, the lack of a major evolutionary response to the end-Triassic event, gives support for the hypothesis that ocean acidification was involved in the dramatic extinctions of many calcifying taxa. doi:10.1002/mmng.201000017

Manipulation of Auditory Inputs as Rehabilitation Therapy for Maladaptive Auditory Cortical Reorganization

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Hidehiko Okamoto

2018-01-01

Full Text Available Neurophysiological and neuroimaging data suggest that the brains of not only children but also adults are reorganized based on sensory inputs and behaviors. Plastic changes in the brain are generally beneficial; however, maladaptive cortical reorganization in the auditory cortex may lead to hearing disorders such as tinnitus and hyperacusis. Recent studies attempted to noninvasively visualize pathological neural activity in the living human brain and reverse maladaptive cortical reorganization by the suitable manipulation of auditory inputs in order to alleviate detrimental auditory symptoms. The effects of the manipulation of auditory inputs on maladaptively reorganized brain were reviewed herein. The findings obtained indicate that rehabilitation therapy based on the manipulation of auditory inputs is an effective and safe approach for hearing disorders. The appropriate manipulation of sensory inputs guided by the visualization of pathological brain activities using recent neuroimaging techniques may contribute to the establishment of new clinical applications for affected individuals.

Constraints on Enhanced Extinction Resulting from Extinction Treatment in the Presence of an Added Excitor

Science.gov (United States)

Urcelay, Gonzalo P.; Lipatova, Olga; Miller, Ralph R.

2009-01-01

Three Pavlovian fear conditioning experiments with rats as subjects explored the effect of extinction in the presence of a concurrent excitor. Our aim was to explore this particular treatment, documented in previous studies to deepen extinction, with novel control groups to shed light on the processes involved in extinction. Relative to subjects…

Magneto-optical extinction trend inversion in ferrofluids

Energy Technology Data Exchange (ETDEWEB)

Shulyma, S.I., E-mail: kiw_88@mail.ru; Tanygin, B.M., E-mail: b.m.tanygin@gmail.com; Kovalenko, V.F.; Petrychuk, M.V.

2016-10-15

Effects of pulse magnetic field on the optical transmission properties of thin ferrofluid (FF) layers were experimentally investigated. It was observed that, under an influence of an external uniform magnetic field, pulses applied to the samples surfaces in normal direction decrease the optical transmission with further returning it to its original state, even before the end of the field pulse. The dependencies of the observed effects on the magnetic pulse magnitude and the samples thickness were investigated. The experimental results are explained using FF columnar aggregates growth and lateral coalescence under influence of a magnetic field, leading to a light scattering type Rayleigh-to-Mie transition. Further evolution of this process comes to a geometrical optics scale and respective macroscopic observable opaque FF columnar aggregates emergence. These changes of optical transmission are non-monotonic during the magnetic field pulse duration with minimal value in the case of Mie scattering, which is known as a magneto-optical extinction trend inversion. The residual inversion was detected after the external magnetic field pulse falling edge. Using molecular dynamics simulation, we showed that a homogeneous external magnetic field is enough for the formation of columnar aggregates and their fusion. The results clarify the known Li theory (Li et al., 2004, 2007), implying an inhomogeneous field as a required prerequisite for the magneto-optical extinction trend inversion phenomenon. - Highlights: • Ferrofluid columnar aggregates have been observed in a homogeneous magnetic field. • Magneto-optical extinction trend inversion is related to the Mie light scattering. • Crucial role of columnar aggregates growth and lateral coalescence has been revealed. • Residual extinction trend inversion was observed after the field switch off.

Magneto-optical extinction trend inversion in ferrofluids

International Nuclear Information System (INIS)

Shulyma, S.I.; Tanygin, B.M.; Kovalenko, V.F.; Petrychuk, M.V.

2016-01-01

Effects of pulse magnetic field on the optical transmission properties of thin ferrofluid (FF) layers were experimentally investigated. It was observed that, under an influence of an external uniform magnetic field, pulses applied to the samples surfaces in normal direction decrease the optical transmission with further returning it to its original state, even before the end of the field pulse. The dependencies of the observed effects on the magnetic pulse magnitude and the samples thickness were investigated. The experimental results are explained using FF columnar aggregates growth and lateral coalescence under influence of a magnetic field, leading to a light scattering type Rayleigh-to-Mie transition. Further evolution of this process comes to a geometrical optics scale and respective macroscopic observable opaque FF columnar aggregates emergence. These changes of optical transmission are non-monotonic during the magnetic field pulse duration with minimal value in the case of Mie scattering, which is known as a magneto-optical extinction trend inversion. The residual inversion was detected after the external magnetic field pulse falling edge. Using molecular dynamics simulation, we showed that a homogeneous external magnetic field is enough for the formation of columnar aggregates and their fusion. The results clarify the known Li theory (Li et al., 2004, 2007), implying an inhomogeneous field as a required prerequisite for the magneto-optical extinction trend inversion phenomenon. - Highlights: • Ferrofluid columnar aggregates have been observed in a homogeneous magnetic field. • Magneto-optical extinction trend inversion is related to the Mie light scattering. • Crucial role of columnar aggregates growth and lateral coalescence has been revealed. • Residual extinction trend inversion was observed after the field switch off.

Long-Lasting Crossmodal Cortical Reorganization Triggered by Brief Postnatal Visual Deprivation.

Science.gov (United States)

Collignon, Olivier; Dormal, Giulia; de Heering, Adelaide; Lepore, Franco; Lewis, Terri L; Maurer, Daphne

2015-09-21

Animal and human studies have demonstrated that transient visual deprivation early in life, even for a very short period, permanently alters the response properties of neurons in the visual cortex and leads to corresponding behavioral visual deficits. While it is acknowledged that early-onset and longstanding blindness leads the occipital cortex to respond to non-visual stimulation, it remains unknown whether a short and transient period of postnatal visual deprivation is sufficient to trigger crossmodal reorganization that persists after years of visual experience. In the present study, we characterized brain responses to auditory stimuli in 11 adults who had been deprived of all patterned vision at birth by congenital cataracts in both eyes until they were treated at 9 to 238 days of age. When compared to controls with typical visual experience, the cataract-reversal group showed enhanced auditory-driven activity in focal visual regions. A combination of dynamic causal modeling with Bayesian model selection indicated that this auditory-driven activity in the occipital cortex was better explained by direct cortico-cortical connections with the primary auditory cortex than by subcortical connections. Thus, a short and transient period of visual deprivation early in life leads to enduring large-scale crossmodal reorganization of the brain circuitry typically dedicated to vision. Copyright © 2015 Elsevier Ltd. All rights reserved.

Extinction of H II regions

International Nuclear Information System (INIS)

Israel, F.P.; Kennicutt, R.C.

1980-01-01

Visual extinction of H II regions in nine nearby galaxies as derived from the ratio of the radio continuum emission to H-alpha emission is systematically larger than visual extinction deduced from the Balmer lines alone, if one assumes a value Av/E(B-V) 3. An optically-limited sample of about 30 extragalactic H II regions has a mean extinction of 1.7 m in the visual while about 1.2 m is not seen in the reddening of the Balmer lines. Both reddening and extinction decreases with increasing galactic radius, at least for M33 and M101

A reconciliation of extinction theories

International Nuclear Information System (INIS)

Sabine, T.M.

1988-01-01

The differences between previous theoretical treatments of extinction based on the Darwin intensity equations arise because of the different functional form chosen for the coupling constant σ. When the same function is used these theories make closely similar predictions. It is shown that a limiting condition on integrated intensity as the crystal size increases puts restrictions on the functions which may be used. A Lorentzian or Fresnellian function can be used for primary extinction while secondary extinction requires a Gaussian, rectangular or triangular function. An analytical expression is given for the variation in the value of the extinction factor with scattering angle. (orig.)

The ethics of reviving long extinct species.

Science.gov (United States)

Sandler, Ronald

2014-04-01

There now appears to be a plausible pathway for reviving species that have been extinct for several decades, centuries, or even millennia. I conducted an ethical analysis of de-extinction of long extinct species. I assessed several possible ethical considerations in favor of pursuing de-extinction: that it is a matter of justice; that it would reestablish lost value; that it would create new value; and that society needs it as a conservation last resort. I also assessed several possible ethical arguments against pursuing de-extinction: that it is unnatural; that it could cause animal suffering; that it could be ecologically problematic or detrimental to human health; and that it is hubristic. There are reasons in favor of reviving long extinct species, and it can be ethically acceptable to do so. However, the reasons in favor of pursuing de-extinction do not have to do with its usefulness in species conservation; rather, they concern the status of revived species as scientific and technological achievements, and it would be ethically problematic to promote de-extinction as a significant conservation strategy, because it does not prevent species extinctions, does not address the causes of extinction, and could be detrimental to some species conservation efforts. Moreover, humanity does not have a responsibility or obligation to pursue de-extinction of long extinct species, and reviving them does not address any urgent problem. Therefore, legitimate ecological, political, animal welfare, legal, or human health concerns associated with a de-extinction (and reintroduction) must be thoroughly addressed for it to be ethically acceptable. © 2013 Society for Conservation Biology.

Press/Pulse: Explaining selective terrestrial extinctions at the Cretaceous/Palaeogene boundary

Science.gov (United States)

Arens, Nan Crystal

2010-05-01

Single-cause mass extinction scenarios require extreme conditions to generate sufficiently strong kill mechanisms. Such dire effects are commonly at odds with the taxonomic selectivity that characterizes most extinction events. In response, some researchers have proposed that the interaction of a variety of factors typify episodes of elevated extinction. Previous work (Arens & West 2008 Paleobiology 34:456-471) has shown that a combination of press and pulse disturbances increases the probability of elevated extinction. The press/pulse contrast is borrowed from community ecology, where researchers have long recognized that the ecological response to long-term stress differs from that of an instantaneous catastrophe. Scaled to the macroevolutionary level, press disturbances alter community composition by placing multigenerational stress on populations. Press disturbances do not necessarily cause mortality, but reduce population size by a variety of mechanisms such as curtailed reproduction. Pulse disturbances are sudden catastrophic events that cause extensive mortality. Either press or pulse disturbances of sufficient magnitude can cause extinction, however elevated extinction occurs more commonly during the coincidence of lower-magnitude press and pulse events. The Cretaceous/Palaeogene (K/P) extinction is one of the best examples of a press/pulse extinction. Deccan Trap volcanism, which straddled the K/P boundary, altered atmospheric composition and climate. This episodic volcanism likely contributed to the climate instability observed in terrestrial ecosystems and exerted press stress. Pulse disturbance was produced by bolide impact, which punctuated the end of the Cretaceous. The press/pulse mechanism also more effectively explains selectivity in terrestrial vertebrate and plant extinctions at the K/P boundary than do single-mechanisms scenarios. For example, why do environmentally sensitive vertebrates such as amphibians experience no extinction? And why do

Immediate Extinction Causes a Less Durable Loss of Performance than Delayed Extinction following Either Fear or Appetitive Conditioning

Science.gov (United States)

Woods, Amanda M.; Bouton, Mark E.

2008-01-01

Five experiments with rat subjects compared the effects of immediate and delayed extinction on the durability of extinction learning. Three experiments examined extinction of fear conditioning (using the conditioned emotional response method), and two experiments examined extinction of appetitive conditioning (using the food-cup entry method). In…

Homeland Security: Scope of the Secretary's Reorganization Authority

National Research Council Canada - National Science Library

Vina, Stephen R

2005-01-01

...). Section 872 of the Homeland Security Act gives the Secretary of Homeland Security the authority to reorganize "functions" and "organizational units" within the Department either independently, 60...

Similar processes but different environmental filters for soil bacterial and fungal community composition turnover on a broad spatial scale.

Directory of Open Access Journals (Sweden)

Nicolas Chemidlin Prévost-Bouré

Full Text Available Spatial scaling of microorganisms has been demonstrated over the last decade. However, the processes and environmental filters shaping soil microbial community structure on a broad spatial scale still need to be refined and ranked. Here, we compared bacterial and fungal community composition turnovers through a biogeographical approach on the same soil sampling design at a broad spatial scale (area range: 13300 to 31000 km2: i to examine their spatial structuring; ii to investigate the relative importance of environmental selection and spatial autocorrelation in determining their community composition turnover; and iii to identify and rank the relevant environmental filters and scales involved in their spatial variations. Molecular fingerprinting of soil bacterial and fungal communities was performed on 413 soils from four French regions of contrasting environmental heterogeneity (Landes

Periodicity in extinction and the problem of catastrophism in the history of life

Science.gov (United States)

Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

1989-01-01

The hypothesis that extinction events have recurred periodically over the last quarter billion years is greatly strengthened by new data on the stratigraphic ranges of marine animal genera. In the interval from the Permian to Recent, these data encompass some 13,000 generic extinctions, providing a more sensitive indicator of species-level extinctions than previously used familial data. Extinction time series computed from the generic data display nine strong peaks that are nearly uniformly spaced at 26 Ma intervals over the last 270 Ma. Most of these peaks correspond to extinction events recognized in more detailed, if limited, biostratigraphic studies. These new data weaken or negate most arguments against periodicity, which have involved criticisms of the taxonomic data base, sampling intervals, chronometric time scales, and statistical methods used in previous analyses. The criticisms are reviewed in some detail and various new calculations and simulations, including one assessing the effects of paraphyletic taxa, are presented. Although the new data strengthen the case for periodicity, they offer little new insight into the deriving mechanism behind the pattern. However, they do suggest that many of the periodic events may not have been catastrophic, occurring instead over several stratigraphic stages or substages.

The reorganization of the Russian hydrocarbons industry: an overview

International Nuclear Information System (INIS)

Locatelli, C.

1995-01-01

The purpose of this article is to present the main guidelines for the reorganization of the Russian hydrocarbon industry. Specifically, it focuses on the economic conditions concerning the constitution of Russian oil companies in an uncertain environment. In Russia, one of the main problems is to create autonomous energy enterprises. The main conclusion is that up to now the reorganization has been essentially juridical, connected with the constitution of joint stock companies. From an economic point of view, the organizational model behind these joint stock companies is not very well defined and lacks clearly defined coordination mechanisms. (author)

Localized extinction of an arboreal desert lizard caused by habitat fragmentation

Science.gov (United States)

Munguia-Vega, Adrian; Rodriguez-Estrella, Ricardo; Shaw, William W.; Culver, Melanie

2013-01-01

We adopted a species’ perspective for predicting extinction risk in a small, endemic, and strictly scansorial lizard (Urosaurus nigricaudus), in an old (∼60 year) and highly fragmented (8% habitat remaining) agricultural landscape from the Sonoran Desert, Mexico. We genotyped 10 microsatellite loci in 280 individuals from 11 populations in fragmented and continuous habitat. Individual dispersal was restricted to less than 400 m, according to analyses of spatial autocorrelation and spatially explicit Bayesian assignment methods. Within this scale, continuous areas and narrow washes with native vegetation allowed high levels of gene flow over tens of kilometers. In the absence of the native vegetation, cleared areas and highways were identified as partial barriers. In contrast, outside the scale of dispersal, cleared areas behaved as complete barriers, and surveys corroborated the species went extinct after a few decades in all small (less than 45 ha), isolated habitat fragments. No evidence for significant loss of genetic diversity was found, but results suggested fragmentation increased the spatial scale of movements, relatedness, genetic structure, and potentially affected sex-biased dispersal. A plausible threshold of individual dispersal predicted only 23% of all fragments in the landscape were linked with migration from continuous habitat, while complete barriers isolated the majority of fragments. Our study suggested limited dispersal, coupled with an inability to use a homogeneous and hostile matrix without vegetation and shade, could result in frequent time-delayed extinctions of small ectotherms in highly fragmented desert landscapes, particularly considering an increase in the risk of overheating and a decrease in dispersal potential induced by global warming.

Behavioral tagging of extinction learning.

Science.gov (United States)

de Carvalho Myskiw, Jociane; Benetti, Fernando; Izquierdo, Iván

2013-01-15

Extinction of contextual fear in rats is enhanced by exposure to a novel environment at 1-2 h before or 1 h after extinction training. This effect is antagonized by administration of protein synthesis inhibitors anisomycin and rapamycin into the hippocampus, but not into the amygdala, immediately after either novelty or extinction training, as well as by the gene expression blocker 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole administered after novelty training, but not after extinction training. Thus, this effect can be attributed to a mechanism similar to synaptic tagging, through which long-term potentiation can be enhanced by other long-term potentiations or by exposure to a novel environment in a protein synthesis-dependent fashion. Extinction learning produces a tag at the appropriate synapses, whereas novelty learning causes the synthesis of plasticity-related proteins that are captured by the tag, strengthening the synapses that generated this tag.

Extinction of Harrington's mountain goat

International Nuclear Information System (INIS)

Mead, J.I.; Martin, P.S.; Euler, R.C.; Long, A.; Jull, A.J.T.; Toolin, L.J.; Donahue, D.J.; Linick, T.W.

1986-01-01

Keratinous horn sheaths of the extinct Harrington's mountain goat, Oreamnos harringtoni, were recovered at or near the surface of dry caves of the Grand Canyon, Arizona. Twenty-three separate specimens from two caves were dated nondestructively by the tandem accelerator mass spectrometer (TAMS). Both the TAMS and the conventional dates indicate that Harrington's mountain goat occupied the Grand Canyon for at least 19,000 years prior to becoming extinct by 11,160 +/- 125 radiocarbon years before present. The youngest average radiocarbon dates on Shasta ground sloths, Nothrotheriops shastensis, from the region are not significantly younger than those on extinct mountain goats. Rather than sequential extinction with Harrington's mountain goat disappearing from the Grand Canyon before the ground sloths, as one might predict in view of evidence of climatic warming at the time, the losses were concurrent. Both extinctions coincide with the regional arrival of Clovis hunters

Open-field exposure facilitates consummatory extinction.

Science.gov (United States)

Justel, Nadia; Psyrdellis, Mariana; Pautassi, Ricardo M

2016-12-07

During extinction, the organism learns that a conditioned stimulus or a conditioned response is no longer associated with an unconditioned stimulus, and as a consequence, a decrement in the response is presented. The exposure to novel situations (e.g. exploration of a novel open field) has been used widely to modulate (i.e. either enhance or deteriorate) learning and memory. The aim of the present study was to test whether open-field exposure could modulate consummatory extinction. The results indicated that open-field exposure accelerated the extinction response (i.e. experimental animals provided novelty exposure had lower consummatory behavior than control animals) when applied before - but not after - the first extinction trial, or when applied before the second extinction trial. The results suggest that environmental treatments such as novelty exposure provide a valuable, nonpharmacological alternative to potentially modulate extinction processes.

Amount of fear extinction changes its underlying mechanisms.

Science.gov (United States)

An, Bobae; Kim, Jihye; Park, Kyungjoon; Lee, Sukwon; Song, Sukwoon; Choi, Sukwoo

2017-07-03

There has been a longstanding debate on whether original fear memory is inhibited or erased after extinction. One possibility that reconciles this uncertainty is that the inhibition and erasure mechanisms are engaged in different phases (early or late) of extinction. In this study, using single-session extinction training and its repetition (multiple-session extinction training), we investigated the inhibition and erasure mechanisms in the prefrontal cortex and amygdala of rats, where neural circuits underlying extinction reside. The inhibition mechanism was prevalent with single-session extinction training but faded when single-session extinction training was repeated. In contrast, the erasure mechanism became prevalent when single-session extinction training was repeated. Moreover, ablating the intercalated neurons of amygdala, which are responsible for maintaining extinction-induced inhibition, was no longer effective in multiple-session extinction training. We propose that the inhibition mechanism operates primarily in the early phase of extinction training, and the erasure mechanism takes over after that.

Broad-Scale Genetic Diversity of Cannabis for Forensic Applications.

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Christophe Dufresnes

Full Text Available Cannabis (hemp and marijuana is an iconic yet controversial crop. On the one hand, it represents a growing market for pharmaceutical and agricultural sectors. On the other hand, plants synthesizing the psychoactive THC produce the most widespread illicit drug in the world. Yet, the difficulty to reliably distinguish between Cannabis varieties based on morphological or biochemical criteria impedes the development of promising industrial programs and hinders the fight against narcotrafficking. Genetics offers an appropriate alternative to characterize drug vs. non-drug Cannabis. However, forensic applications require rapid and affordable genotyping of informative and reliable molecular markers for which a broad-scale reference database, representing both intra- and inter-variety variation, is available. Here we provide such a resource for Cannabis, by genotyping 13 microsatellite loci (STRs in 1 324 samples selected specifically for fibre (24 hemp varieties and drug (15 marijuana varieties production. We showed that these loci are sufficient to capture most of the genome-wide diversity patterns recently revealed by NGS data. We recovered strong genetic structure between marijuana and hemp and demonstrated that anonymous samples can be confidently assigned to either plant types. Fibres appear genetically homogeneous whereas drugs show low (often clonal diversity within varieties, but very high genetic differentiation between them, likely resulting from breeding practices. Based on an additional test dataset including samples from 41 local police seizures, we showed that the genetic signature of marijuana cultivars could be used to trace crime scene evidence. To date, our study provides the most comprehensive genetic resource for Cannabis forensics worldwide.

Broad-Scale Genetic Diversity of Cannabis for Forensic Applications.

Science.gov (United States)

Dufresnes, Christophe; Jan, Catherine; Bienert, Friederike; Goudet, Jérôme; Fumagalli, Luca

2017-01-01

Cannabis (hemp and marijuana) is an iconic yet controversial crop. On the one hand, it represents a growing market for pharmaceutical and agricultural sectors. On the other hand, plants synthesizing the psychoactive THC produce the most widespread illicit drug in the world. Yet, the difficulty to reliably distinguish between Cannabis varieties based on morphological or biochemical criteria impedes the development of promising industrial programs and hinders the fight against narcotrafficking. Genetics offers an appropriate alternative to characterize drug vs. non-drug Cannabis. However, forensic applications require rapid and affordable genotyping of informative and reliable molecular markers for which a broad-scale reference database, representing both intra- and inter-variety variation, is available. Here we provide such a resource for Cannabis, by genotyping 13 microsatellite loci (STRs) in 1 324 samples selected specifically for fibre (24 hemp varieties) and drug (15 marijuana varieties) production. We showed that these loci are sufficient to capture most of the genome-wide diversity patterns recently revealed by NGS data. We recovered strong genetic structure between marijuana and hemp and demonstrated that anonymous samples can be confidently assigned to either plant types. Fibres appear genetically homogeneous whereas drugs show low (often clonal) diversity within varieties, but very high genetic differentiation between them, likely resulting from breeding practices. Based on an additional test dataset including samples from 41 local police seizures, we showed that the genetic signature of marijuana cultivars could be used to trace crime scene evidence. To date, our study provides the most comprehensive genetic resource for Cannabis forensics worldwide.

Extinction of Chained Instrumental Behaviors: Effects of Procurement Extinction on Consumption Responding

Science.gov (United States)

Thrailkill, Eric A.; Bouton, Mark E.

2015-01-01

Instrumental behavior often consists of sequences or chains of responses that minimally include procurement behaviors that enable subsequent consumption behaviors. In such chains, behavioral units are linked by access to one another and eventually to a primary reinforcer, such as food or a drug. The present experiments examined the effects of extinguishing procurement responding on consumption responding after training of a discriminated heterogeneous instrumental chain. Rats learned to make a procurement response (e.g., pressing a lever) in the presence of a distinctive discriminative stimulus; making that response led to the presentation of a second discriminative stimulus that set the occasion for a consumption response (e.g., pulling a chain), which then produced a food-pellet reinforcer. Experiment 1 showed that extinction of either the full procurement-consumption chain or procurement alone weakened the consumption response tested in isolation. Experiment 2 replicated the procurement extinction effect and further demonstrated that the opportunity to make the procurement response, as opposed to simple exposure to the procurement stimulus alone, was required. In Experiment 3, rats learned 2 distinct discriminated heterogeneous chains; extinction of 1 procurement response specifically weakened the consumption response that had been associated with it. The results suggest that learning to inhibit the procurement response may produce extinction of consumption responding through mediated extinction. The experiments suggest the importance of an associative analysis of instrumental behavior chains. PMID:25915751

Biological correlates of extinction risk in bats.

Science.gov (United States)

Jones, Kate E; Purvis, Andy; Gittleman, John L

2003-04-01

We investigated patterns and processes of extinction and threat in bats using a multivariate phylogenetic comparative approach. Of nearly 1,000 species worldwide, 239 are considered threatened by the International Union for Conservation of Nature and Natural Resources (IUCN) and 12 are extinct. Small geographic ranges and low wing aspect ratios are independently found to predict extinction risk in bats, which explains 48% of the total variance in IUCN assessments of threat. The pattern and correlates of extinction risk in the two bat suborders are significantly different. A higher proportion (4%) of megachiropteran species have gone extinct in the last 500 years than microchiropteran bats (0.3%), and a higher proportion is currently at risk of extinction (Megachiroptera: 34%; Microchiroptera: 22%). While correlates of microchiropteran extinction risk are the same as in the order as a whole, megachiropteran extinction is correlated more with reproductive rate and less with wing morphology. Bat extinction risk is not randomly distributed phylogenetically: closely related species have more similar levels of threat than would be expected if extinction risk were random. Given the unbalanced nature of the evolutionary diversification of bats, it is probable that the amount of phylogenetic diversity lost if currently threatened taxa disappear may be greater than in other clades with numerically more threatened species.

Evidence and mapping of extinction debts for global forest-dwelling reptiles, amphibians and mammals

Science.gov (United States)

Chen, Youhua; Peng, Shushi

2017-03-01

Evidence of extinction debts for the global distributions of forest-dwelling reptiles, mammals and amphibians was tested and the debt magnitude was estimated and mapped. By using different correlation tests and variable importance analysis, the results showed that spatial richness patterns for the three forest-dwelling terrestrial vertebrate groups had significant and stronger correlations with past forest cover area and other variables in the 1500 s, implying the evidence for extinction debts. Moreover, it was likely that the extinction debts have been partially paid, given that their global richness patterns were also significantly correlated with contemporary forest variables in the 2000 s (but the absolute magnitudes of the correlation coefficients were usually smaller than those calculated for historical forest variables). By utilizing species-area relationships, spatial extinction-debt magnitudes for the three vertebrate groups at the global scale were estimated and the hotspots of extinction debts were identified. These high-debt hotspots were generally situated in areas that did not spatially overlap with hotspots of species richness or high extinction-risk areas based on IUCN threatened status to a large extent. This spatial mismatch pattern suggested that necessary conservation efforts should be directed toward high-debt areas that are still overlooked.

Enhanced Operant Extinction and Prefrontal Excitability in a Mouse Model of Angelman Syndrome.

Science.gov (United States)

Sidorov, Michael S; Judson, Matthew C; Kim, Hyojin; Rougie, Marie; Ferrer, Alejandra I; Nikolova, Viktoriya D; Riddick, Natallia V; Moy, Sheryl S; Philpot, Benjamin D

2018-03-14

Angelman syndrome (AS), a neurodevelopmental disorder associated with intellectual disability, is caused by loss of maternal allele expression of UBE3A in neurons. Mouse models of AS faithfully recapitulate disease phenotypes across multiple domains, including behavior. Yet in AS, there has been only limited study of behaviors encoded by the prefrontal cortex, a region broadly involved in executive function and cognition. Because cognitive impairment is a core feature of AS, it is critical to develop behavioral readouts of prefrontal circuit function in AS mouse models. One such readout is behavioral extinction, which has been well described mechanistically and relies upon prefrontal circuits in rodents. Here we report exaggerated operant extinction in male AS model mice, concomitant with enhanced excitability in medial prefrontal neurons from male and female AS model mice. Abnormal behavior was specific to operant extinction, as two other prefrontally dependent tasks (cued fear extinction and visuospatial discrimination) were largely normal in AS model mice. Inducible deletion of Ube3a during adulthood was not sufficient to drive abnormal extinction, supporting the hypothesis that there is an early critical period for development of cognitive phenotypes in AS. This work represents the first formal experimental analysis of prefrontal circuit function in AS, and identifies operant extinction as a useful experimental paradigm for modeling cognitive aspects of AS in mice. SIGNIFICANCE STATEMENT Prefrontal cortex encodes "high-level" cognitive processes. Thus, understanding prefrontal function is critical in neurodevelopmental disorders where cognitive impairment is highly penetrant. Angelman syndrome is a neurodevelopmental disorder associated with speech and motor impairments, an outwardly happy demeanor, and intellectual disability. We describe a behavioral phenotype in a mouse model of Angelman syndrome and related abnormalities in prefrontal cortex function. We

Agricultural Set-aside Programs and Grassland Birds: Insights from Broad-scale Population Trends

Directory of Open Access Journals (Sweden)

S. Riffell

2008-10-01

Full Text Available The Conservation Reserve Program (CRP is a voluntary set-aside program in the United States designed to amelioratesoil erosion, control crop overproduction, enhance water quality, and provide wildlife habitat by replacing crops with other forms of land cover. Because CRP includes primarily grass habitats, it has great potential to benefitdeclining North American grassland bird populations. We looked at the change in national and state population trends of grassland birds and related changes to cover-specific CRP variables (previous research grouped all CRP practices. Changes in national trends after the initiation of the CRP were inconclusive, but we observed signficant bird-CRP relations at the state level. Most bird-CRP relations were positive, except for some species associated with habitats that CRP replaced. Practice- and configuration-specific CRP variables were related to grassland bird trends, rather than a generic measure of all CRP types combined. Considering all CRP land as a single, distinct habitat type may obscure actual relations between birds and set-aside characteristics. Understanding and predictingthe effects of set-aside programs (like CRP or agri-environment schemes on grassland birds is complex and difficult. Because available broad-scale datasets are less than adequate, studies should be conducted at a variety of spatial and temporal scales.

Ultraviolet extinction in M-supergiant circumstellar envelopes

International Nuclear Information System (INIS)

Buss, R.H. Jr.; Snow, T.P. Jr.

1986-01-01

Using International Ultraviolet (IUS) archival low-dispersion spectra, ultraviolet spectral extinctions were derived for the circumstellar envelopes of two M supergiants: HD 60414 and HD 213310. The observed stellar systems belong to a class of widely-separated spectroscopic binaries that are called VV Cephei stars. The total extinction was calculated by dividing the reddened fluxes with unreddened comparison fluxes of similar stars (g B2.5 for HD 213310 and a normalized s+B3 for HD 60414) from the reference atlas. After substracting the interstellar extinctions, which were estimated from the E(B-V) reddening of nearby stars, the resultant circumstellar extinctions were normalized at about 3.5 inverse microns. Not only is the 2175 A extinction bump absent in the circumstellar extinctions, but the far-ultraviolet extinction rise is also absent. The rather flat, ultraviolet extinction curves were interpreted as signatures of a population of noncarbonaceous, oxygen-rich grains with diameters larger than the longest observed wavelength

Mass extinctions: Ecological selectivity and primary production

Science.gov (United States)

Rhodes, Melissa Clark; Thayer, Charles W.

1991-09-01

If mass extinctions were caused by reduced primary productivity, then extinctions should be concentrated among animals with starvation-susceptible feeding modes, active lifestyles, and high-energy budgets. The stratigraphic ranges (by stage) of 424 genera of bivalves and 309 genera of articulate brachiopods suggest that there was an unusual reduction of primary productivity at the Cretaceous/Tertiary (K/T) boundary extinction. For bivalves at the K/T, there were (1) selective extinction of suspension feeders and other susceptible trophic categories relative to deposit feeders and other resistant categories, and (2) among suspension feed-ers, selective extinction of bivalves with active locomotion. During the Permian-Triassic (P/Tr) extinction and Jurassic background time, extinction rates among suspension feeders were greater for articulate brachiopods than for bivalves. But during the K/T event, extinction rates of articulates and suspension-feeding bivalves equalized, possibly because the low-energy budgets of articulates gave them an advantage when food was scarce.

3,4-Methylenedioxymethamphetamine facilitates fear extinction learning.

Science.gov (United States)

Young, M B; Andero, R; Ressler, K J; Howell, L L

2015-09-15

Acutely administered 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') has been proposed to have long-term positive effects on post-traumatic stress disorder (PTSD) symptoms when combined with psychotherapy. No preclinical data support a mechanistic basis for these claims. Given the persistent nature of psychotherapeutic gains facilitated by MDMA, we hypothesized that MDMA improves fear extinction learning, a key process in exposure-based therapies for PTSD. In these experiments, mice were first exposed to cued fear conditioning and treated with drug vehicle or MDMA before extinction training 2 days later. MDMA was administered systemically and also directly targeted to brain structures known to contribute to extinction. In addition to behavioral measures of extinction, changes in mRNA levels of brain-derived neurotrophic factor (Bdnf) and Fos were measured after MDMA treatment and extinction. MDMA (7.8 mg kg(-1)) persistently and robustly enhanced long-term extinction when administered before extinction training. MDMA increased the expression of Fos in the amygdala and medial prefrontal cortex (mPFC), whereas increases in Bdnf expression were observed only in the amygdala after extinction training. Extinction enhancements were recapitulated when MDMA (1 μg) was infused directly into the basolateral complex of the amygdala (BLA), and enhancement was abolished when BDNF signaling was inhibited before extinction. These findings suggest that MDMA enhances fear memory extinction through a BDNF-dependent mechanism, and that MDMA may be a useful adjunct to exposure-based therapies for PTSD and other anxiety disorders characterized by altered fear learning.

Elucidating the mechanisms of fear extinction in developing animals: a special case of NMDA receptor-independent extinction in adolescent rats.

Science.gov (United States)

Bisby, Madelyne A; Baker, Kathryn D; Richardson, Rick

2018-04-01

NMDA receptors (NMDARs) are considered critical for the consolidation of extinction but recent work challenges this assumption. Namely, NMDARs are not required for extinction retention in infant rats as well as when extinction training occurs for a second time (i.e., reextinction) in adult rats. In this study, a possible third instance of NMDAR-independent extinction was tested. Although adolescents typically exhibit impaired extinction retention, rats that are conditioned as juveniles and then given extinction training as adolescents (JuvCond-AdolesExt) have good extinction retention. Unexpectedly, this good extinction retention is not associated with an up-regulation of a synaptic plasticity marker in the medial prefrontal cortex, a region implicated in extinction consolidation. In the current study, rats received either the noncompetitive NMDAR antagonist MK801 (0.1 mg/kg, s.c.) or saline before extinction training. In several experiments, rats conditioned and extinguished as juveniles, adolescents, or adults exhibited impaired extinction retention after MK801 compared to saline, but this effect was not observed in JuvCond-AdolesExt rats. Further experiments ruled out several alternative explanations for why NMDAR antagonism did not affect extinction retention in adolescents extinguishing fear learned as a juvenile. These results illustrate yet another circumstance in which NMDARs are not required for successful extinction retention and highlight the complexity of fear inhibition across development. © 2018 Bisby et al.; Published by Cold Spring Harbor Laboratory Press.

An investigation of the interstellar extinction

International Nuclear Information System (INIS)

Roche, P.F.; Aitken, D.K.; Melbourne Univ., Point Cook

1984-01-01

The 10 μm extinction towards six WC8 or WC9 Wolf-Rayet stars is investigated. All objects show smooth dust emission suffering silicate absorption with depths well correlated with the extinction in the visible. The de-reddened spectra are well represented by emission from featureless grain components, possibly from iron or carbon grains. The extinction to the stars is found to be dominantly interstellar in origin with little extinction from the circumstellar shell. (author)

AN ANALYSIS OF THE SHAPES OF INTERSTELLAR EXTINCTION CURVES. VI. THE NEAR-IR EXTINCTION LAW

International Nuclear Information System (INIS)

Fitzpatrick, E. L.; Massa, D.

2009-01-01

We combine new observations from the Hubble Space Telescope's Advanced Camera of Survey with existing data to investigate the wavelength dependence of near-IR (NIR) extinction. Previous studies suggest a power law form for NIR extinction, with a 'universal' value of the exponent, although some recent observations indicate that significant sight line-to-sight line variability may exist. We show that a power-law model for the NIR extinction provides an excellent fit to most extinction curves, but that the value of the power, β, varies significantly from sight line to sight line. Therefore, it seems that a 'universal NIR extinction law' is not possible. Instead, we find that as β decreases, R(V) ≡ A(V)/E(B - V) tends to increase, suggesting that NIR extinction curves which have been considered 'peculiar' may, in fact, be typical for different R(V) values. We show that the power-law parameters can depend on the wavelength interval used to derive them, with the β increasing as longer wavelengths are included. This result implies that extrapolating power-law fits to determine R(V) is unreliable. To avoid this problem, we adopt a different functional form for NIR extinction. This new form mimics a power law whose exponent increases with wavelength, has only two free parameters, can fit all of our curves over a longer wavelength baseline and to higher precision, and produces R(V) values which are consistent with independent estimates and commonly used methods for estimating R(V). Furthermore, unlike the power-law model, it gives R(V)s that are independent of the wavelength interval used to derive them. It also suggests that the relation R(V) = -1.36 E(K-V)/(E(B-V)) - 0.79 can estimate R(V) to ±0.12. Finally, we use model extinction curves to show that our extinction curves are in accord with theoretical expectations, and demonstrate how large samples of observational quantities can provide useful constraints on the grain properties.

Unresolved trauma in mothers: intergenerational effects and the role of reorganization

Science.gov (United States)

Iyengar, Udita; Kim, Sohye; Martinez, Sheila; Fonagy, Peter; Strathearn, Lane

2014-01-01

A mother's unresolved trauma may interfere with her ability to sensitively respond to her infant, thus affecting the development of attachment in her own child, and potentially contributing to the intergenerational transmission of trauma. One novel construct within the Dynamic Maturational Model of Attachment and Adaptation (DMM) coding of the Adult Attachment Interview (AAI) is “reorganization,” a process whereby speakers are actively changing their understanding of past and present experiences and moving toward attachment security. We conducted a study of mothers with unresolved trauma, exploring their own attachment classification, attachment outcomes of their children, and the potential effects of reorganization on child attachment. Forty-seven first-time mothers participated in the AAI during pregnancy, and returned with their child at 11 months to assess child attachment using the Strange Situation Procedure. Mothers with and without unresolved trauma were compared. We found that mothers with unresolved trauma had insecure attachment themselves and were more likely to have infants with insecure attachment. However, the one exception was that all of the mothers with unresolved trauma who were reorganizing toward secure attachment had infants with secure attachment. These preliminary findings suggest that mothers who are reorganizing may be able to more sensitively respond to their child's cues, contributing to the development of secure attachment. While our results need to be replicated in a larger cohort, this study is the first to explore the construct of reorganization and its potential relationship with child attachment. If confirmed in future studies, it may provide clinical insight into the intergenerational transmission of insecure attachment within the context of unresolved trauma. PMID:25225490

Mass extinction efficiency and extinction hygroscopicity of ambient PM2.5 in urban China.

Science.gov (United States)

Cheng, Zhen; Ma, Xin; He, Yujie; Jiang, Jingkun; Wang, Xiaoliang; Wang, Yungang; Sheng, Li; Hu, Jiangkai; Yan, Naiqiang

2017-07-01

The ambient PM 2.5 pollution problem in China has drawn substantial international attentions. The mass extinction efficiency (MEE) and hygroscopicity factor (f(RH)) of PM 2.5 can be readily applied to study the impacts on atmospheric visibility and climate. The few previous investigations in China only reported results from pilot studies and are lack of spatial representativeness. In this study, hourly average ambient PM 2.5 mass concentration, relative humidity, and atmospheric visibility data from China national air quality and meteorological monitoring networks were retrieved and analyzed. It includes 24 major Chinese cities from nine city-clusters with the period of October 2013 to September 2014. Annual average extinction coefficient in urban China was 759.3±258.3Mm -1 , mainly caused by dry PM 2.5 (305.8.2±131.0Mm -1 ) and its hygroscopicity (414.6±188.1Mm -1 ). High extinction coefficient values were resulted from both high ambient PM 2.5 concentration (68.5±21.7µg/m 3 ) and high relative humidity (69.7±8.6%). The PM 2.5 mass extinction efficiency varied from 2.87 to 6.64m 2 /g with an average of 4.40±0.84m 2 /g. The average extinction hygroscopic factor f(RH=80%) was 2.63±0.45. The levels of PM 2.5 mass extinction efficiency and hygroscopic factor in China were in comparable range with those found in developed countries in spite of the significant diversities among all 24 cities. Our findings help to establish quantitative relationship between ambient extinction coefficient (visual range) and PM 2.5 & relative humidity. It will reduce the uncertainty of extinction coefficient estimation of ambient PM 2.5 in urban China which is essential for the research of haze pollution and climate radiative forcing. Copyright © 2017 Elsevier Inc. All rights reserved.

Hierarchical spatial structure of stream fish colonization and extinction

Science.gov (United States)

Hitt, N.P.; Roberts, J.H.

2012-01-01

Spatial variation in extinction and colonization is expected to influence community composition over time. In stream fish communities, local species richness (alpha diversity) and species turnover (beta diversity) are thought to be regulated by high extinction rates in headwater streams and high colonization rates in downstream areas. We evaluated the spatiotemporal structure of fish communities in streams originally surveyed by Burton and Odum 1945 (Ecology 26: 182-194) in Virginia, USA and explored the effects of species traits on extinction and colonization dynamics. We documented dramatic changes in fish community structure at both the site and stream scales. Of the 34 fish species observed, 20 (59%) were present in both time periods, but 11 (32%) colonized the study area and three (9%) were extirpated over time. Within streams, alpha diversity increased in two of three streams but beta diversity decreased dramatically in all streams due to fish community homogenization caused by colonization of common species and extirpation of rare species. Among streams, however, fish communities differentiated over time. Regression trees indicated that reproductive life-history traits such as spawning mound construction, associations with mound-building species, and high fecundity were important predictors of species persistence or colonization. Conversely, native fishes not associated with mound-building exhibited the highest rates of extirpation from streams. Our results demonstrate that stream fish colonization and extinction dynamics exhibit hierarchical spatial structure and suggest that mound-building fishes serve as keystone species for colonization of headwater streams.

Homeland Security: Scope of the Secretary's Reorganization Authority

National Research Council Canada - National Science Library

Vina, Stephen R

2005-01-01

.... While many of the proposed changes may be effectuated administratively, some might require legislative action due to limits on reorganization authority under the Homeland Security Act of 2002 (P.L. 107-296...

Temporal evolution of brain reorganization under cross-modal training: insights into the functional architecture of encoding and retrieval networks

Science.gov (United States)

Likova, Lora T.

2015-03-01

specialization in terms of either encoding or retrieval as a function of the stage of learning. Moreover, several distinct patterns of learning-evolution within the patches as a function of their anatomical location, implying a complex reorganization of the object processing sub-networks through the learning period. These first findings of complex patterns of training-based encoding/retrieval reorganization thus have broad implications for a newly emerging view of the perception/memory interactions and their reorganization through the learning process. Note that the temporal evolution of these forms of extended functional reorganization could not be uncovered with conventional assessment paradigms used in the traditional approaches to functional mapping, which may therefore have to be revisited. Moreover, as the present results are obtained in learning under life-long blindness, they imply modality-independent operations, transcending the usual tight association with visual processing. The present approach of memory drawing training in blindness, has the dual-advantage of being both non-visual and causal intervention, which makes it a promising 'scalpel' to disentangle interactions among diverse cognitive functions.

Database Reorganization in Parallel Disk Arrays with I/O Service Stealing

Science.gov (United States)

Zabback, Peter; Onyuksel, Ibrahim; Scheuermann, Peter; Weikum, Gerhard

1996-01-01

We present a model for data reorganization in parallel disk systems that is geared towards load balancing in an environment with periodic access patterns. Data reorganization is performed by disk cooling, i.e. migrating files or extents from the hottest disks to the coldest ones. We develop an approximate queueing model for determining the effective arrival rates of cooling requests and discuss its use in assessing the costs versus benefits of cooling.

Mass extinctions and supernova explosions

OpenAIRE

Korschinek, Gunther

2016-01-01

A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation, o...

Dinosaur morphological diversity and the end-Cretaceous extinction.

Science.gov (United States)

Brusatte, Stephen L; Butler, Richard J; Prieto-Márquez, Albert; Norell, Mark A

2012-05-01

The extinction of non-avian dinosaurs 65 million years ago is a perpetual topic of fascination, and lasting debate has focused on whether dinosaur biodiversity was in decline before end-Cretaceous volcanism and bolide impact. Here we calculate the morphological disparity (anatomical variability) exhibited by seven major dinosaur subgroups during the latest Cretaceous, at both global and regional scales. Our results demonstrate both geographic and clade-specific heterogeneity. Large-bodied bulk-feeding herbivores (ceratopsids and hadrosauroids) and some North American taxa declined in disparity during the final two stages of the Cretaceous, whereas carnivorous dinosaurs, mid-sized herbivores, and some Asian taxa did not. Late Cretaceous dinosaur evolution, therefore, was complex: there was no universal biodiversity trend and the intensively studied North American record may reveal primarily local patterns. At least some dinosaur groups, however, did endure long-term declines in morphological variability before their extinction.

No disillusions in auditory extinction: perceiving a melody comprised of unperceived notes

Directory of Open Access Journals (Sweden)

Leon Y Deouell

2008-03-01

Full Text Available The formation of coherent percepts requires grouping together spatio-temporally disparate sensory inputs. Two major questions arise: (1 is awareness necessary for this process; and (2 can non-conscious elements of the sensory input be grouped into a conscious perceptµ To address this question, we tested two patients suffering from severe left auditory extinction following right hemisphere damage. In extinction, patients are unaware of the presence of left side stimuli when they are presented simultaneously with right side stimuli. We used the ‘scale illusion’ to test whether extinguished tones on the left can be incorporated into the content of conscious awareness. In the scale illusion, healthy listeners obtain the illusion of distinct melodies, which are the result of grouping of information from both ears into illusory auditory streams. We show that the two patients were susceptible to the scale illusion while being consciously unaware of the stimuli presented on their left. This suggests that awareness is not necessary for auditory grouping and non-conscious elements can be incorporated into a conscious percept.

DESCRIPTION OF THE ORGANIZATIONAL AND TECHNOLOGICAL PROCESSES ON THE GROUND OF THE BASIC MODEL OF THE CYCLE OF REORGANIZATION

Directory of Open Access Journals (Sweden)

Gazaryan Robert Kamoevich

2012-12-01

Full Text Available The objective of this scientific research is application of the basic model of interaction between phases of a cycle of reorganization of organizational and technological processes underway at industrial enterprises. The authors describe interactions between all six phases of the process of reorganization within the framework of the basic model of a cycle that contemplates organizational and technological processes. Engineering studies are necessary to check for the feasibility of reorganization of industrial enterprises and application of results extracted from the design documentation with a view to reorganization of production activities and construction operations. Upon completion of the decision-making process concerning the need for reorganization in accordance with the basic model of interaction between phases, there occurs restructuring that incorporates processes of design and construction. The authors have demonstrated that reorganization of the basic model cycle should be used in the design of organizational and technological processes with a view to the integrated consideration of reorganization of enterprises in order to comprehend and improve the efficiency of reorganization at each stage, as well as the control over the reorganization of a construction facility.

Global warming and extinctions of endemic species from biodiversity hotspots.

Science.gov (United States)

Jay R. Malcolm; Canran Liu; Ronald P. Neilson; Lara Hansen; Lee. Hannah

2006-01-01

Global warming is a key threat to biodiversity, but few researchers have assessed the magnitude of this threat at the global scale. We used major vegetation types (biomes) as proxies for natural habitats and, based on projected future biome distributions under doubled-C02 climates, calculated changes in habitat areas and associated extinctions of...

Body Size, Extinction Risk and Knowledge Bias in New World Snakes

Science.gov (United States)

Vilela, Bruno; Villalobos, Fabricio; Rodríguez, Miguel Ángel; Terribile, Levi Carina

2014-01-01

Extinction risk and body size have been found to be related in various vertebrate groups, with larger species being more at risk than smaller ones. We checked whether this was also the case for snakes by investigating extinction risk–body size relationships in the New World's Colubroidea species. We used the IUCN Red List risk categories to assign each species to one of two broad levels of threat (Threatened and Non-Threatened) or to identify it as either Data Deficient or Not-Evaluated by the IUCN. We also included the year of description of each species in our analysis as this could affect the level of threat assigned to it (earlier described species had more time to gather information about them, which might have facilitated their evaluation). Also, species detectability could be a function of body size, with larger species tending to be described earlier, which could have an impact in extinction risk–body size relationships. We found a negative relationship between body size and description year, with large-bodied species being described earlier. Description year also varied among risk categories, with Non-Threatened species being described earlier than Threatened species and both species groups earlier than Data Deficient species. On average, Data Deficient species also presented smaller body sizes, while no size differences were detected between Threatened and Non-Threatened species. So it seems that smaller body sizes are related with species detectability, thus potentially affecting both when a species is described (smaller species tend to be described more recently) as well as the amount of information gathered about it (Data Deficient species tend to be smaller). Our data also indicated that if Data Deficient species were to be categorized as Threatened in the future, snake body size and extinction risk would be negatively related, contrasting with the opposite pattern commonly observed in other vertebrate groups. PMID:25409293

Extinction debt: a challenge for biodiversity conservation.

Science.gov (United States)

Kuussaari, Mikko; Bommarco, Riccardo; Heikkinen, Risto K; Helm, Aveliina; Krauss, Jochen; Lindborg, Regina; Ockinger, Erik; Pärtel, Meelis; Pino, Joan; Rodà, Ferran; Stefanescu, Constantí; Teder, Tiit; Zobel, Martin; Steffan-Dewenter, Ingolf

2009-10-01

Local extinction of species can occur with a substantial delay following habitat loss or degradation. Accumulating evidence suggests that such extinction debts pose a significant but often unrecognized challenge for biodiversity conservation across a wide range of taxa and ecosystems. Species with long generation times and populations near their extinction threshold are most likely to have an extinction debt. However, as long as a species that is predicted to become extinct still persists, there is time for conservation measures such as habitat restoration and landscape management. Standardized long-term monitoring, more high-quality empirical studies on different taxa and ecosystems and further development of analytical methods will help to better quantify extinction debt and protect biodiversity.

Political and technical issues of coal fire extinction in the Kyoto framework

Science.gov (United States)

Meyer, U.; Chen-Brauchler, D.; Rüter, H.; Fischer, C.; Bing, K.

2009-04-01

It is a highly desirable effort to extinguish as much coal fires as possible in short time to prevent large losses of energy resources and to minimise CO2 and other exhaust gas releases from such sources. Unfortunately, extinguishing coal fires needs massive financial investments, skilled man power, suited technology and a long time. Even mid to small scale coal fires need several months of extinguishing measures and of monitoring time after extinction resulting in expenditures of a minimum of several hundred thousand Euros. Large companies might be willing to spend money for coal fire extinction measures but smaller holdings or regional governments might not have the monetary resources for it. Since there is no law in China that demands coal fire extinction, measures under the Kyoto framework may be applied to sell CO2 certificates for prevented emissions from extinguished coal fires and thus used as a financial stimulus for coal fire extinction activities. The set-up for methodologies and project designs is especially complex for coal fire extinction measures and thus for necessary exploration, evaluation and monitoring using geophysical and remote sensing methods. A brief overview of most important formal and technical aspects is given to outline the conditions for a potentially successful CDM application on coal fires based on geophysical observations and numerical modelling.

Heterostyly accelerates diversification via reduced extinction in primroses

Science.gov (United States)

de Vos, Jurriaan M.; Hughes, Colin E.; Schneeweiss, Gerald M.; Moore, Brian R.; Conti, Elena

2014-01-01

The exceptional species diversity of flowering plants, exceeding that of their sister group more than 250-fold, is especially evident in floral innovations, interactions with pollinators and sexual systems. Multiple theories, emphasizing flower–pollinator interactions, genetic effects of mating systems or high evolvability, predict that floral evolution profoundly affects angiosperm diversification. However, consequences for speciation and extinction dynamics remain poorly understood. Here, we investigate trajectories of species diversification focusing on heterostyly, a remarkable floral syndrome where outcrossing is enforced via cross-compatible floral morphs differing in placement of their respective sexual organs. Heterostyly evolved at least 20 times independently in angiosperms. Using Darwin's model for heterostyly, the primrose family, we show that heterostyly accelerates species diversification via decreasing extinction rates rather than increasing speciation rates, probably owing to avoidance of the negative genetic effects of selfing. However, impact of heterostyly appears to differ over short and long evolutionary time-scales: the accelerating effect of heterostyly on lineage diversification is manifest only over long evolutionary time-scales, whereas recent losses of heterostyly may prompt ephemeral bursts of speciation. Our results suggest that temporal or clade-specific conditions may ultimately determine the net effects of specific traits on patterns of species diversification. PMID:24759859

MICROLENSING OF QUASAR BROAD EMISSION LINES: CONSTRAINTS ON BROAD LINE REGION SIZE

Energy Technology Data Exchange (ETDEWEB)

Guerras, E.; Mediavilla, E. [Instituto de Astrofisica de Canarias, Via Lactea S/N, La Laguna E-38200, Tenerife (Spain); Jimenez-Vicente, J. [Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Campus de Fuentenueva, E-18071 Granada (Spain); Kochanek, C. S. [Department of Astronomy and the Center for Cosmology and Astroparticle Physics, The Ohio State University, 4055 McPherson Lab, 140 West 18th Avenue, Columbus, OH 43221 (United States); Munoz, J. A. [Departamento de Astronomia y Astrofisica, Universidad de Valencia, E-46100 Burjassot, Valencia (Spain); Falco, E. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Motta, V. [Departamento de Fisica y Astronomia, Universidad de Valparaiso, Avda. Gran Bretana 1111, Valparaiso (Chile)

2013-02-20

We measure the differential microlensing of the broad emission lines between 18 quasar image pairs in 16 gravitational lenses. We find that the broad emission lines are in general weakly microlensed. The results show, at a modest level of confidence (1.8{sigma}), that high ionization lines such as C IV are more strongly microlensed than low ionization lines such as H{beta}, indicating that the high ionization line emission regions are more compact. If we statistically model the distribution of microlensing magnifications, we obtain estimates for the broad line region size of r{sub s} = 24{sup +22} {sub -15} and r{sub s} = 55{sup +150} {sub -35} lt-day (90% confidence) for the high and low ionization lines, respectively. When the samples are divided into higher and lower luminosity quasars, we find that the line emission regions of more luminous quasars are larger, with a slope consistent with the expected scaling from photoionization models. Our estimates also agree well with the results from local reveberation mapping studies.

Late Pleistocene Megafaunal Extinction Consistent With YDB Impact Hypothesis at Younger Dryas Onset

Science.gov (United States)

Kennett, J. P.; Kennett, D. J.

2008-12-01

associated with abrupt and major vegetation changes, abrupt cooling, and widespread biomass burning at the onset of the Younger Dryas over North America. The stratigraphic and chronologic data are consistent with megafaunal extinction being caused by continental-scale ecosystem disruption due to an ET impact.

Inter-hemispheric language functional reorganization in low-grade glioma patients after tumour surgery.

Science.gov (United States)

Kristo, Gert; Raemaekers, Mathijs; Rutten, Geert-Jan; de Gelder, Beatrice; Ramsey, Nick F

2015-03-01

Despite many claims of functional reorganization following tumour surgery, empirical studies that investigate changes in functional activation patterns are rare. This study investigates whether functional recovery following surgical treatment in patients with a low-grade glioma in the left hemisphere is linked to inter-hemispheric reorganization. Based on literature, we hypothesized that reorganization would induce changes in the spatial pattern of activation specifically in tumour homologue brain areas in the healthy right hemisphere. An experimental group (EG) of 14 patients with a glioma in the left hemisphere near language related brain areas, and a control group of 6 patients with a glioma in the right, non-language dominant hemisphere were scanned before and after resection. In addition, an age and gender matched second control group of 18 healthy volunteers was scanned twice. A verb generation task was used to map language related areas and a novel technique was used for data analysis. Contrary to our hypothesis, we found that functional recovery following surgery of low-grade gliomas cannot be linked to functional reorganization in language homologue brain areas in the healthy, right hemisphere. Although elevated changes in the activation pattern were found in patients after surgery, these were largest in brain areas in proximity to the surgical resection, and were very similar to the spatial pattern of the brain shift following surgery. This suggests that the apparent perilesional functional reorganization is mostly caused by the brain shift as a consequence of surgery. Perilesional functional reorganization can however not be excluded. The study suggests that language recovery after transient post-surgical language deficits involves recovery of functioning of the presurgical language system. Copyright © 2014 Elsevier Ltd. All rights reserved.

Incorporating climate and ocean change into extinction risk assessments for 82 coral species.

Science.gov (United States)

Brainard, Russell E; Weijerman, Mariska; Eakin, C Mark; McElhany, Paul; Miller, Margaret W; Patterson, Matt; Piniak, Gregory A; Dunlap, Matthew J; Birkeland, Charles

2013-12-01

Many marine invertebrate species facing potential extinction have uncertain taxonomies and poorly known demographic and ecological traits. Uncertainties are compounded when potential extinction drivers are climate and ocean changes whose effects on even widespread and abundant species are only partially understood. The U.S. Endangered Species Act mandates conservation management decisions founded on the extinction risk to species based on the best available science at the time of consideration-requiring prompt action rather than awaiting better information. We developed an expert-opinion threat-based approach that entails a structured voting system to assess extinction risk from climate and ocean changes and other threats to 82 coral species for which population status and threat response information was limited. Such methods are urgently needed because constrained budgets and manpower will continue to hinder the availability of desired data for many potentially vulnerable marine species. Significant species-specific information gaps and uncertainties precluded quantitative assessments of habitat loss or population declines and necessitated increased reliance on demographic characteristics and threat vulnerabilities at genus or family levels. Adapting some methods (e.g., a structured voting system) used during other assessments and developing some new approaches (e.g., integrated assessment of threats and demographic characteristics), we rated the importance of threats contributing to coral extinction risk and assessed those threats against population status and trend information to evaluate each species' extinction risk over the 21st century. This qualitative assessment resulted in a ranking with an uncertainty range for each species according to their estimated likelihood of extinction. We offer guidance on approaches for future biological extinction risk assessments, especially in cases of data-limited species likely to be affected by global-scale threats

The extinction of the dinosaurs.

Science.gov (United States)

Brusatte, Stephen L; Butler, Richard J; Barrett, Paul M; Carrano, Matthew T; Evans, David C; Lloyd, Graeme T; Mannion, Philip D; Norell, Mark A; Peppe, Daniel J; Upchurch, Paul; Williamson, Thomas E

2015-05-01

Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

Noradrenergic stimulation modulates activation of extinction-related brain regions and enhances contextual extinction learning without affecting renewal

Directory of Open Access Journals (Sweden)

Silke eLissek

2015-02-01

Full Text Available Renewal in extinction learning describes the recovery of an extinguished response if the extinction context differs from the context present during acquisition and recall. Attention may have a role in contextual modulation of behavior and contribute to the renewal effect, while noradrenaline is involved in attentional processing. In this functional magnetic resonance imaging (fMRI study we investigated the role of the noradrenergic system for behavioral and brain activation correlates of contextual extinction and renewal, with a particular focus upon hippocampus and ventromedial PFC, which have crucial roles in processing of renewal. Healthy human volunteers received a single dose of the NA reuptake inhibitor atomoxetine prior to extinction learning. During extinction of previously acquired cue-outcome associations, cues were presented in a novel context (ABA or in the acquisition context (AAA. In recall, all cues were again presented in the acquisition context. Atomoxetine participants (ATO showed significantly faster extinction compared to placebo (PLAC. However, atomoxetine did not affect renewal. Hippocampal activation was higher in ATO during extinction and recall, as was ventromedial PFC activation, except for ABA recall. Moreover, ATO showed stronger recruitment of insula, anterior cingulate, and dorsolateral/orbitofrontal PFC. Across groups, cingulate, hippocampus and vmPFC activity during ABA extinction correlated with recall performance, suggesting high relevance of these regions for processing the renewal effect. In summary, the noradrenergic system appears to be involved in the modification of established associations during extinction learning and thus has a role in behavioral flexibility. The assignment of an association to a context and the subsequent decision on an adequate response, however, presumably operate largely independently of noradrenergic mechanisms.

Mixed evidence for the potential of non-invasive transcutaneous vagal nerve stimulation to improve the extinction and retention of fear.

Science.gov (United States)

Burger, A M; Verkuil, B; Fenlon, H; Thijs, L; Cools, L; Miller, H C; Vervliet, B; Van Diest, I

2017-10-01

Extinction memories are fragile and their formation has been proposed to partially rely on vagus nerve activity. We tested whether stimulating the auricular branch of the vagus (transcutaneous VNS; tVNS) accelerates extinction and reduces spontaneous recovery of fear. Forty-two healthy students participated in a 3-day fear conditioning study, where we tested fear acquisition (day 1), fear extinction (day 2) and the retention of the extinction memory (day 3). During extinction, participants were randomly allocated to receive tVNS or sham stimulation concurrently with each CS presentation. During the acquisition and retention phases, all participants received sham stimulation. Indexes of fear included US-expectancy, startle blink EMG and skin conductance responses. Results showed successful acquisition and extinction of fear in all measures. tVNS facilitated the extinction of declarative fear (US expectancy ratings), but did not promote a stronger retention of the declarative extinction memory. No clear effects of tVNS on extinction and retention of extinction were found for the psychophysiological indexes. The present findings provide tentative indications that tVNS could be a promising tool to improve fear extinction and call for larger scale studies to replicate these effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bilateral reorganization of the dentate gyrus in hippocampal sclerosis

Science.gov (United States)

Thom, M; Martinian, L; Catarino, C; Yogarajah, M; Koepp, M J.; Caboclo, L; Sisodiya, S M.

2009-01-01

Background: Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. Methods: Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21–96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. Results: Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. Conclusion: Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon. GLOSSARY AED = antiepileptic drug; CA1p = CA1-predominant hippocampal sclerosis; CHS = classical hippocampal sclerosis; EFG = end folium gliosis; EFS = end folium sclerosis; GCD = granule cell dispersion; GCL = granule cell layer; HS = hippocampal sclerosis; MFS = mossy fiber sprouting; MTLE = mesial temporal lobe epilepsy; NPY = neuropeptide Y; ROI = region of interest; SE = status epilepticus; TLE = temporal lobe epilepsy. PMID:19710404

Unraveling the drivers of community dissimilarity and species extinction in fragmented landscapes.

Science.gov (United States)

Banks-Leite, Cristina; Ewers, Robert M; Metzger, Jean Paul

2012-12-01

Communities in fragmented landscapes are often assumed to be structured by species extinction due to habitat loss, which has led to extensive use of the species-area relationship (SAR) in fragmentation studies. However, the use of the SAR presupposes that habitat loss leads species to extinction but does not allow for extinction to be offset by colonization of disturbed-habitat specialists. Moreover, the use of SAR assumes that species richness is a good proxy of community changes in fragmented landscapes. Here, we assessed how communities dwelling in fragmented landscapes are influenced by habitat loss at multiple scales; then we estimated the ability of models ruled by SAR and by species turnover in successfully predicting changes in community composition, and asked whether species richness is indeed an informative community metric. To address these issues, we used a data set consisting of 140 bird species sampled in 65 patches, from six landscapes with different proportions of forest cover in the Atlantic Forest of Brazil. We compared empirical patterns against simulations of over 8 million communities structured by different magnitudes of the power-law SAR and with species-specific rules to assign species to sites. Empirical results showed that, while bird community composition was strongly influenced by habitat loss at the patch and landscape scale, species richness remained largely unaffected. Modeling results revealed that the compositional changes observed in the Atlantic Forest bird metacommunity were only matched by models with either unrealistic magnitudes of the SAR or by models ruled by species turnover, akin to what would be observed along natural gradients. We show that, in the presence of such compositional turnover, species richness is poorly correlated with species extinction, and z values of the SAR strongly underestimate the effects of habitat loss. We suggest that the observed compositional changes are driven by each species reaching its

Proposal and Research Direction of Soil Mass Organic Reorganization

Science.gov (United States)

Zhang, Lu; Han, Jichang

2018-01-01

Land engineering as a new discipline has been temporarily outrageous. The proposition of soil body organic reorganization undoubtedly enriches the research content for the construction of land engineering disciplines. Soil body organic reconstruction is designed to study how to realize the ecological ecology of the land by studying the external force of nature, to study the influence of sunlight, wind and water on soil body, how to improve the soil physical structure, to further strengthen the research of biological enzymes and microbes, and promote the release and utilization of beneficial inert elements in soil body. The emerging of frontier scientific research issues with soil body organic reorganization to indicate directions for the future development of soil engineering.

Changes in Allostatic Load during workplace reorganization.

Science.gov (United States)

Carlsson, Rikke Hinge; Hansen, Åse Marie; Nielsen, Martin Lindhardt; Blønd, Morten; Netterstrøm, Bo

2017-12-01

Allostatic Load (AL) represents the strain on the body produced by repeated physiologic or allostatic responses activated during stressful situations. Several cross-sectional studies have found empirical substantiation for the relationship between impaired psychosocial work environment and high AL. The aim of this longitudinal study is to investigate changes in AL during workplace reorganization that has been shown to cause impaired psychosocial work environment. Moreover, we aim to investigate the association between changes in AL and changes in psychosocial work environment (job strain, effort-reward imbalance) and psychological distress (stress symptoms and perceived stress). A major reorganization of non-state public offices was effectuated in Denmark on 1 January 2007. In 2006 and 2008, we collected clinical and questionnaire data from 359 participants, 265 women and 94 men, employed in seven municipality or county administrations. Four municipalities and one county merged with others, while one municipality and one county remained unmerged. We calculated the AL score based on 13 physiological markers reflecting stress responses of the cardiovascular, metabolic, neuroendocrine and immune systems. We analysed changes in AL from 2006 to 2008. AL increased significantly during workplace reorganization in the whole study group but we observed only a tendency of significant increase in AL in the merger group compared with the control group. Moreover, we observed no association between the changes in AL and changes in psychosocial work environment and psychological distress. This result leaves the conclusion unclear but contributes to the limited research in this area with a longitudinal design and focus on low-risk levels and small changes in AL in healthy people as predictor of future disease. Copyright © 2017 Elsevier Inc. All rights reserved.

Trophic redundancy reduces vulnerability to extinction cascades.

Science.gov (United States)

Sanders, Dirk; Thébault, Elisa; Kehoe, Rachel; Frank van Veen, F J

2018-03-06

Current species extinction rates are at unprecedentedly high levels. While human activities can be the direct cause of some extinctions, it is becoming increasingly clear that species extinctions themselves can be the cause of further extinctions, since species affect each other through the network of ecological interactions among them. There is concern that the simplification of ecosystems, due to the loss of species and ecological interactions, increases their vulnerability to such secondary extinctions. It is predicted that more complex food webs will be less vulnerable to secondary extinctions due to greater trophic redundancy that can buffer against the effects of species loss. Here, we demonstrate in a field experiment with replicated plant-insect communities, that the probability of secondary extinctions is indeed smaller in food webs that include trophic redundancy. Harvesting one species of parasitoid wasp led to secondary extinctions of other, indirectly linked, species at the same trophic level. This effect was markedly stronger in simple communities than for the same species within a more complex food web. We show that this is due to functional redundancy in the more complex food webs and confirm this mechanism with a food web simulation model by highlighting the importance of the presence and strength of trophic links providing redundancy to those links that were lost. Our results demonstrate that biodiversity loss, leading to a reduction in redundant interactions, can increase the vulnerability of ecosystems to secondary extinctions, which, when they occur, can then lead to further simplification and run-away extinction cascades. Copyright © 2018 the Author(s). Published by PNAS.

MicroRNA-Mediated Rescue of Fear Extinction Memory by miR-144-3p in Extinction-Impaired Mice.

Science.gov (United States)

Murphy, Conor P; Li, Xiang; Maurer, Verena; Oberhauser, Michael; Gstir, Ronald; Wearick-Silva, Luis Eduardo; Viola, Thiago Wendt; Schafferer, Simon; Grassi-Oliveira, Rodrigo; Whittle, Nigel; Hüttenhofer, Alexander; Bredy, Timothy W; Singewald, Nicolas

2017-06-15

MicroRNA (miRNA)-mediated control of gene expression suggests that miRNAs are interesting targets and/or biomarkers in the treatment of anxiety- and trauma-related disorders, where often memory-associated gene expression is adversely affected. The role of miRNAs in the rescue of impaired fear extinction was assessed using the 129S1/SvlmJ (S1) mouse model of impaired fear extinction. miRNA microarray analysis, reverse transcription polymerase chain reaction, fluorescent in situ hybridization, lentiviral overexpression, and Luciferase reporter assays were used to gain insight into the mechanisms underlying miRNA-mediated normalization of deficient fear extinction. Rescuing impaired fear extinction via dietary zinc restriction was associated with differential expression of miRNAs in the amygdala. One candidate, miR-144-3p, robustly expressed in the basolateral amygdala, showed specific extinction-induced, but not fear-induced, increased expression in both extinction-rescued S1 mice and extinction-intact C57BL/6 (BL6) mice. miR-144-3p upregulation and effects on subsequent behavioral adaption was assessed in S1 and BL6 mice. miR-144-3p overexpression in the basolateral amygdala rescued impaired fear extinction in S1 mice, led to enhanced fear extinction acquisition in BL6 mice, and furthermore protected against fear renewal in BL6 mice. miR-144-3p targets a number of genes implicated in the control of plasticity-associated signaling cascades, including Pten, Spred1, and Notch1. In functional interaction studies, we revealed that the miR-144-3p target, PTEN, colocalized with miR-144-3p in the basolateral amygdala and showed functional downregulation following successful fear extinction in S1 mice. These findings identify a fundamental role of miR-144-3p in the rescue of impaired fear extinction and suggest this miRNA as a viable target in developing novel treatments for posttraumatic stress disorder and related disorders. Copyright © 2017 Society of Biological

Intergalactic extinction and the deceleration parameter

International Nuclear Information System (INIS)

Meinel, R.

1981-01-01

The deceleration parameter q 0 is calculated from the relation between apparent magnitudes m of the brightest galaxies in clusters and their redshifts z considering an intergalactic extinction. The calculation is valid for a Friedman universe, homogeneously filled with dust grains, assuming the extinction to be 0.5 mag at z = 1 and aΛ -1 -law of extinction (according to Oleak and Schmidt 1976). Using the m,z-values of Kristian, Sandage, and Westphal (1978) a formal value of q 0 approximately 2.1 is obtained instead of q 0 approximately 1.6 without consideration of intergalactic extinction. (author)

Climate predictors of late quaternary extinctions

DEFF Research Database (Denmark)

Nogués-Bravo, David; Ohlemüller, Ralf; Batra, Persaram

2010-01-01

Between 50,000 and 3,000 years before present (BP) 65% of mammal genera weighing over 44 kg went extinct, together with a lower proportion of small mammals. Why species went extinct in such large numbers is hotly debated. One of the arguments proposes that climate changes underlie Late Quaternary...... extinctions, but global quantitative evidence for this hypothesis is still lacking. We test the potential role of global climate change on the extinction of mammals during the Late Quaternary. Our results suggest that continents with the highest climate footprint values, in other words, with climate changes...... of greater magnitudes during the Late Quaternary, witnessed more extinctions than continents with lower climate footprint values, with the exception of South America. Our results are consistent across species with different body masses, reinforcing the view that past climate changes contributed to global...

Search for jet extinction in the inclusive jet-pt spectrum from proton-proton collisions at sqrt(s) = 8 TeV

Energy Technology Data Exchange (ETDEWEB)

Khachatryan, Vardan [Yerevan Physcis Institute (Armenia); et al.,

2014-08-01

The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale.

Biogeographic and bathymetric determinants of brachiopod extinction and survival during the Late Ordovician mass extinction

DEFF Research Database (Denmark)

Finnegan, Seth; Mac Ørum Rasmussen, Christian; Harper, David A. T.

2016-01-01

–Early Silurian genus extinctions and evaluate which extinction drivers are best supported by the data. The first (latest Katian) pulse of the LOME preferentially affected genera restricted to deeper waters or to relatively narrow (less than 35°) palaeolatitudinal ranges. This pattern is only observed...... in the latest Katian, suggesting that it reflects drivers unique to this interval. Extinction of exclusively deeper-water genera implies that changes in water mass properties such as dissolved oxygen content played an important role. Extinction of genera with narrow latitudinal ranges suggests that interactions...... between shifting climate zones and palaeobiogeography may also have been important. We test the latter hypothesis by estimating whether each genus would have been able to track habitats within its thermal tolerance range during the greenhouse–icehouse climate transition. Models including these estimates...

Direct measurement of interstellar extinction toward young stars using atomic hydrogen Lyα absorption

Energy Technology Data Exchange (ETDEWEB)

McJunkin, Matthew; France, Kevin; Brown, Alexander [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Schneider, P. C. [Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany); Herczeg, Gregory J. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Hillenbrand, Lynne [California Institute of Technology, Department of Astrophysics, MC105-24, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Schindhelm, Eric [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Edwards, Suzan, E-mail: matthew.mcjunkin@colorado.edu [Five College Astronomy Department, Smith College, Northampton, MA 01063 (United States)

2014-01-10

Interstellar reddening corrections are necessary to reconstruct the intrinsic spectral energy distributions (SEDs) of accreting protostellar systems. The stellar SED determines the heating and chemical processes that can occur in circumstellar disks. Measurement of neutral hydrogen absorption against broad Lyα emission profiles in young stars can be used to obtain the total H I column density (N(H I)) along the line of sight. We measure N(H I) with new and archival ultraviolet observations from the Hubble Space Telescope (HST) of 31 classical T Tauri and Herbig Ae/Be stars. The H I column densities range from log{sub 10}(N(H I)) ≈19.6-21.1, with corresponding visual extinctions of A{sub V} =0.02-0.72 mag, assuming an R{sub V} of 3.1. We find that the majority of the H I absorption along the line of sight likely comes from interstellar rather than circumstellar material. Extinctions derived from new HST blue-optical spectral analyses, previous IR and optical measurements, and new X-ray column densities on average overestimate the interstellar extinction toward young stars compared to the N(H I) values by ∼0.6 mag. We discuss possible explanations for this discrepancy in the context of a protoplanetary disk geometry.

Burnout in health-care professionals during reorganizations and downsizing. A cohort study in nurses

Directory of Open Access Journals (Sweden)

Hall-Lord Marie-Louise

2010-06-01

Full Text Available Abstract Background Burnout is a psychological reaction triggered by interaction between personal characteristics and stress factors. Reorganizations and downsizing with increased workload imply stress for health-care professionals. This is a study of burnout in nurses during a period with two comprehensive reorganizations. Methods In this quasi-experimental retrospective cohort study, burnout was assessed in nurses with long work experience in three surveys during a 30 months' period with two comprehensive reorganizations and downsizing of a hospital unit with mostly seriously ill patients with cancer. Burnout was measured with Bergen Burnout Indicator (BBI at each survey, and "Sense of Coherence" (SOC with Antonovsky's questionnaire at the last survey. Results One man and 45 women aged 30 to 65 years were invited to the surveys. There was a significant increase in burnout during the study period, the mean increase in BBI-score was 12.5 pr year (p Conclusions There was a significant development of burnout in a group of nurses during a period with two reorganizations and downsizing. Burnout was associated with low SOC. Working with seriously ill patients with cancer has probably made the nurses exceptionally vulnerable to the stress and workload related to the reorganizations.

Interstellar extinction in the Large Magellanic Cloud

International Nuclear Information System (INIS)

Nandy, K.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.

1981-01-01

A systematic investigation of interstellar extinction in the ultraviolet as a function of position in the Large Magellanic Cloud has been made from an enlarged sample of reddened and comparison stars distributed throughout the cloud. Except for one star SK-69-108, the most reddened star of our sample, the shape of the extinction curves for the LMC stars do not show significant variations. All curves show an increase in extinction towards 2200 A, but some have maxima near 2200 A, some near 1900 A. It has been shown that the feature of the extinction curve near 1900 A is caused by the mismatch of the stellar F III 1920 A feature. The strength of this 1920 A feature as a function of luminosity and spectral type has been determined. The extinction curves have been corrected for the mismatch of the 1920 feature and a single mean extinction curve for the LMC normalized to Asub(V) = 0 and Esub(B-V) = 1 is presented. For the same value of Esub(B-V) the LMC stars show the 2200 A feature weaker by a factor 2 as compared with the galactic stars. Higher extinction shortward of 2000 A in the LMC extinction curves than that in our Galaxy, as reported in earlier papers, is confirmed. (author)

Immediate extinction promotes the return of fear.

Science.gov (United States)

Merz, Christian J; Hamacher-Dang, Tanja C; Wolf, Oliver T

2016-05-01

Accumulating evidence indicates that immediate extinction is less effective than delayed extinction in attenuating the return of fear. This line of fear conditioning research impacts the proposed onset of psychological interventions after threatening situations. In the present study, forty healthy men were investigated in a differential fear conditioning paradigm with fear acquisition in context A, extinction in context B, followed by retrieval testing in both contexts 24h later to test fear renewal. Differently coloured lights served as conditioned stimuli (CS): two CS (CS+) were paired with an electrical stimulation that served as unconditioned stimulus, the third CS was never paired (CS-). Extinction took place immediately after fear acquisition or 24h later. One CS+ was extinguished whereas the second CS+ remained unextinguished to control for different time intervals between fear acquisition and retrieval testing. Immediate extinction led to larger skin conductance responses during fear retrieval to both the extinguished and unextinguished CS relative to the CS-, indicating a stronger return of fear compared to delayed extinction. Taken together, immediate extinction is less potent than delayed extinction and is associated with a stronger renewal effect. Thus, the time-point of psychological interventions relative to the offset of threatening situations needs to be carefully considered to prevent relapses. Copyright © 2016 Elsevier Inc. All rights reserved.

Quantifying the extent of North American mammal extinction relative to the pre-anthropogenic baseline.

Science.gov (United States)

Carrasco, Marc A; Barnosky, Anthony D; Graham, Russell W

2009-12-16

Earth has experienced five major extinction events in the past 450 million years. Many scientists suggest we are now witnessing a sixth, driven by human impacts. However, it has been difficult to quantify the real extent of the current extinction episode, either for a given taxonomic group at the continental scale or for the worldwide biota, largely because comparisons of pre-anthropogenic and anthropogenic biodiversity baselines have been unavailable. Here, we compute those baselines for mammals of temperate North America, using a sampling-standardized rich fossil record to reconstruct species-area relationships for a series of time slices ranging from 30 million to 500 years ago. We show that shortly after humans first arrived in North America, mammalian diversity dropped to become at least 15%-42% too low compared to the "normal" diversity baseline that had existed for millions of years. While the Holocene reduction in North American mammal diversity has long been recognized qualitatively, our results provide a quantitative measure that clarifies how significant the diversity reduction actually was. If mass extinctions are defined as loss of at least 75% of species on a global scale, our data suggest that North American mammals had already progressed one-fifth to more than halfway (depending on biogeographic province) towards that benchmark, even before industrialized society began to affect them. Data currently are not available to make similar quantitative estimates for other continents, but qualitative declines in Holocene mammal diversity are also widely recognized in South America, Eurasia, and Australia. Extending our methodology to mammals in these areas, as well as to other taxa where possible, would provide a reasonable way to assess the magnitude of global extinction, the biodiversity impact of extinctions of currently threatened species, and the efficacy of conservation efforts into the future.

Quantifying the extent of North American mammal extinction relative to the pre-anthropogenic baseline.

Directory of Open Access Journals (Sweden)

Marc A Carrasco

2009-12-01

Full Text Available Earth has experienced five major extinction events in the past 450 million years. Many scientists suggest we are now witnessing a sixth, driven by human impacts. However, it has been difficult to quantify the real extent of the current extinction episode, either for a given taxonomic group at the continental scale or for the worldwide biota, largely because comparisons of pre-anthropogenic and anthropogenic biodiversity baselines have been unavailable. Here, we compute those baselines for mammals of temperate North America, using a sampling-standardized rich fossil record to reconstruct species-area relationships for a series of time slices ranging from 30 million to 500 years ago. We show that shortly after humans first arrived in North America, mammalian diversity dropped to become at least 15%-42% too low compared to the "normal" diversity baseline that had existed for millions of years. While the Holocene reduction in North American mammal diversity has long been recognized qualitatively, our results provide a quantitative measure that clarifies how significant the diversity reduction actually was. If mass extinctions are defined as loss of at least 75% of species on a global scale, our data suggest that North American mammals had already progressed one-fifth to more than halfway (depending on biogeographic province towards that benchmark, even before industrialized society began to affect them. Data currently are not available to make similar quantitative estimates for other continents, but qualitative declines in Holocene mammal diversity are also widely recognized in South America, Eurasia, and Australia. Extending our methodology to mammals in these areas, as well as to other taxa where possible, would provide a reasonable way to assess the magnitude of global extinction, the biodiversity impact of extinctions of currently threatened species, and the efficacy of conservation efforts into the future.

Optimising Extinction of Conditioned Disgust

NARCIS (Netherlands)

Bosman, Renske C.; Borg, Charmaine; de Jong, Peter J.

2016-01-01

Maladaptive disgust responses are tenacious and resistant to exposure-based interventions. In a similar vein, laboratory studies have shown that conditioned disgust is relatively insensitive to Conditioned Stimulus (CS)-only extinction procedures. The relatively strong resistance to extinction might

Interstellar dust and extinction

International Nuclear Information System (INIS)

Mathis, J.S.

1990-01-01

It is noted that the term interstellar dust refers to materials with rather different properties, and that the mean extinction law of Seaton (1979) or Savage and Mathis (1979) should be replaced by the expression given by Cardelli et al. (1989), using the appropriate value of total-to-selective extinction. The older laws were appropriate for the diffuse ISM but dust in clouds differs dramatically in its extinction law. Dust is heavily processed while in the ISM by being included within clouds and cycled back into the diffuse ISM many times during its lifetime. Hence, grains probably reflect only a trace of their origin, although meteoritic inclusions with isotopic anomalies demonstrate that some tiny particles survive intact from a supernova origin to the present. 186 refs

Impact Theory of Mass Extinctions and the Invertebrate Fossil Record

Science.gov (United States)

Alvarez, Walter; Kauffman, Erle G.; Surlyk, Finn; Alvarez, Luis W.; Asaro, Frank; Michel, Helen V.

1984-03-01

There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consequences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups. Reexamination of data from careful studies of the best sections shows that, in addition to undergoing the decline, four groups (ammonites, cheilostomate bryozoans, brachiopods, and bivalves) were affected by sudden truncations precisely at the iridium anomaly that marks the boundary. The paleontological record thus bears witness to terminal-Cretaceous extinctions on two time scales: a slow decline unrelated to the impact and a sharp truncation synchronous with and probably caused by the impact.

Sleep Strengthens but does Not Reorganize Memory Traces in a Verbal Creativity Task.

Science.gov (United States)

Landmann, Nina; Kuhn, Marion; Maier, Jonathan-Gabriel; Feige, Bernd; Spiegelhalder, Kai; Riemann, Dieter; Nissen, Christoph

2016-03-01

Sleep after learning promotes the quantitative strengthening of new memories. Less is known about the impact of sleep on the qualitative reorganization of memory content. This study tested the hypothesis that sleep facilitates both memory strengthening and reorganization as indexed by a verbal creativity task. Sixty healthy university students (30 female, 30 male, 20-30 years) were investigated in a randomized, controlled parallel-group study with three experimental groups (sleep, sleep deprivation, daytime wakefulness). At baseline, 60 items of the Compound Remote Associate (CRA) task were presented. At retest after the experimental conditions, the same items were presented again together with 20 new control items to disentangle off-line incubation from online performance effects. Sleep significantly strengthened formerly encoded memories in comparison to both wake conditions (improvement in speed of correctly resolved items). Offline reorganization was not enhanced following sleep, but was enhanced following sleep-deprivation in comparison to sleep and daytime wakefulness (solution time of previously incubated, newly solved items). Online performance did not differ between the groups (solution time of new control items). The results support the notion that sleep promotes the strengthening, but not the reorganization, of newly encoded memory traces in a verbal creativity task. Future studies are needed to further determine the impact of sleep on different types of memory reorganization, such as associative thinking, creativity and emotional memory processing, and potential clinical translations, such as the augmentation of psychotherapy through sleep interventions. © 2016 Associated Professional Sleep Societies, LLC.

Mass extinction in poorly known taxa.

Science.gov (United States)

Régnier, Claire; Achaz, Guillaume; Lambert, Amaury; Cowie, Robert H; Bouchet, Philippe; Fontaine, Benoît

2015-06-23

Since the 1980s, many have suggested we are in the midst of a massive extinction crisis, yet only 799 (0.04%) of the 1.9 million known recent species are recorded as extinct, questioning the reality of the crisis. This low figure is due to the fact that the status of very few invertebrates, which represent the bulk of biodiversity, have been evaluated. Here we show, based on extrapolation from a random sample of land snail species via two independent approaches, that we may already have lost 7% (130,000 extinctions) of the species on Earth. However, this loss is masked by the emphasis on terrestrial vertebrates, the target of most conservation actions. Projections of species extinction rates are controversial because invertebrates are essentially excluded from these scenarios. Invertebrates can and must be assessed if we are to obtain a more realistic picture of the sixth extinction crisis.

Compound Stimulus Extinction Reduces Spontaneous Recovery in Humans

Science.gov (United States)

Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

2015-01-01

Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…

Recovery from the most profound mass extinction of all time.

Science.gov (United States)

Sahney, Sarda; Benton, Michael J

2008-04-07

The end-Permian mass extinction, 251 million years (Myr) ago, was the most devastating ecological event of all time, and it was exacerbated by two earlier events at the beginning and end of the Guadalupian, 270 and 260 Myr ago. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. Disaster taxa, such as Lystrosaurus, insinuated themselves into almost every corner of the sparsely populated landscape in the earliest Triassic, and a quick taxonomic recovery apparently occurred on a global scale. However, close study of ecosystem evolution shows that true ecological recovery was slower. After the end-Guadalupian event, faunas began rebuilding complex trophic structures and refilling guilds, but were hit again by the end-Permian event. Taxonomic diversity at the alpha (community) level did not recover to pre-extinction levels; it reached only a low plateau after each pulse and continued low into the Late Triassic. Our data showed that though there was an initial rise in cosmopolitanism after the extinction pulses, large drops subsequently occurred and, counter-intuitively, a surprisingly low level of cosmopolitanism was sustained through the Early and Middle Triassic.

Presurgical fMRI evaluation of cerebral reorganization and motor deficit in patients with tumors and vascular malformations

International Nuclear Information System (INIS)

Baciu, M.; Le Bas, J.F.; Segebarth, C.; Benabid, A.L.

2003-01-01

The aim of this fMRI study was to evaluate the motor reorganization (cerebral plasticity) and the risk of motor deficit in patients presenting with tumors and vascular malformations, within the framework of their pre-surgical planning. Functional MR imaging data was obtained from 17 patients. Ten patients (seven with tumors and three with vascular malformations) presented with motor reorganization. The results of the present study suggest that the evaluation of the cerebral reorganization is an essential step in predicting the risk of motor deficit in patients having surgical indication for treatment. Furthermore, the cerebral reorganization constitutes an important factor for surgical decision

Heterochromatin Reorganization during Early Mouse Development Requires a Single-Stranded Noncoding Transcript

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Miguel Casanova

2013-09-01

Full Text Available The equalization of pericentric heterochromatin from distinct parental origins following fertilization is essential for genome function and development. The recent implication of noncoding transcripts in this process raises questions regarding the connection between RNA and the nuclear organization of distinct chromatin environments. Our study addresses the interrelationship between replication and transcription of the two parental pericentric heterochromatin (PHC domains and their reorganization during early embryonic development. We demonstrate that the replication of PHC is dispensable for its clustering at the late two-cell stage. In contrast, using parthenogenetic embryos, we show that pericentric transcripts are essential for this reorganization independent of the chromatin marks associated with the PHC domains. Finally, our discovery that only reverse pericentric transcripts are required for both the nuclear reorganization of PHC and development beyond the two-cell stage challenges current views on heterochromatin organization.

On the trap of extinction and its elimination

International Nuclear Information System (INIS)

Vitanov, Nikolay K.; Dimitrova, Zlatinka I.; Kantz, Holger

2006-01-01

We investigate the dynamics of a system of three interacting populations in presence of extinction and substitution: each population whose number of individuals drops under some threshold value becomes extinct, and it is substituted by another population with different fitness and different coefficients of interaction with the other populations. We study the influence of extinction on the system states, which in the absence of extinction can be fixed points, limit cycles or chaotic attractors of Shilnikov kind. The extinction can destabilize each of these states. We observe two possible kinds of evolution in the destabilized system: (i) it can remain forever in the trap of extinction, i.e., the extinctions and substitutions of populations continue for indefinitely long time or (ii) it can avoid the trap of extinction by means of the substitution, i.e., the fitness and the coefficients of the interactions between the species move the system attractor away from the zone of the threshold values, the extinction stops, and the system settles on a new attractor. The obtained results are discussed from the point of view of products competing for the preference of buyers that can change their opinion

EARTH SCIENCE: Did Volcanoes Drive Ancient Extinctions?

Science.gov (United States)

Kerr, R A

2000-08-18

With the publication in recent weeks of two papers on a mass extinction 183 million years ago, researchers can add five suggestive cases to the list of extinctions with known causes. These extinctions coincide with massive outpourings of lava, accompanied by signs that global warming threw the ocean-atmosphere system out of whack. Although no one can yet pin any of these mass extinctions with certainty on the volcanic eruptions, scientists say it's unlikely that they're all coincidences.

Extinction rates in North American freshwater fishes, 1900-2010

Science.gov (United States)

Burkhead, Noel M.

2012-01-01

Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean = 7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86 species by 2050.

Reintroducing resurrected species: selecting DeExtinction candidates.

Science.gov (United States)

Seddon, Philip J; Moehrenschlager, Axel; Ewen, John

2014-03-01

Technological advances have raised the controversial prospect of resurrecting extinct species. Species DeExtinction should involve more than the production of biological orphans to be scrutinized in the laboratory or zoo. If DeExtinction is to realize its stated goals of deep ecological enrichment, then resurrected animals must be translocated (i.e., released within suitable habitat). Therefore, DeExtinction is a conservation translocation issue and the selection of potential DeExtinction candidates must consider the feasibility and risks associated with reintroduction. The International Union for the Conservation of Nature (IUCN) Guidelines on Reintroductions and Other Conservation Translocations provide a framework for DeExtinction candidate selection. We translate these Guidelines into ten questions to be addressed early on in the selection process to eliminate unsuitable reintroduction candidates. We apply these questions to the thylacine, Yangtze River Dolphin, and Xerces blue butterfly. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evolution: Postponing Extinction by Polyandry

OpenAIRE

Wade, Michael J.

2010-01-01

Sex-ratio meiotic drive occurs when males produce a predominance of X-chromosome bearing sperm and an inordinate number of daughters. A driving X causes highly female-biased sex ratios and the risk of extinction. Polyandry can rescue a population from extinction.

The 'Hub Disruption Index', a reliable index sensitive to the brain networks reorganization. A study of the contralesional hemisphere in stroke

Directory of Open Access Journals (Sweden)

Maite Termenon

2016-08-01

healthy controls. Using new graph metrics as kappa allows us to show that stroke induces a network-wide pattern of reorganization in the contralesional hemisphere whatever the side of the lesion. Graph modeling combined with measure of reorganization at the level of large-scale networks can become a useful tool in clinic.

Can we avoid the Sixth Mass Extinction? Setting today's extinction crisis in the context of the Big Five

Science.gov (United States)

Barnosky, A. D.

2012-12-01

While the ultimate extinction driver now—Homo sapiens—is unique with respect to the drivers of past extinctions, comparison of parallel neontological and paleontological information helps calibrate how far the so-called Sixth Mass Extinction has progressed and whether it is inevitable. Such comparisons document that rates of extinction today are approaching or exceeding those that characterized the Big Five Mass Extinctions. Continuation of present extinction rates for vertebrates, for example, would result in 75% species loss—the minimum benchmark exhibited in the Big Five extinctions—within 3 to 22 centuries, assuming constant rates of loss and no threshold effects. Preceding and during each of the Big Five, the global ecosystem experienced major changes in climate, atmospheric chemisty, and ocean chemistry—not unlike what is being observed presently. Nevertheless, only 1-2% of well-assessed modern species have been lost over the past five centuries, still far below what characterized past mass extinctions in the strict paleontological sense. For mammals, adding in the end-Pleistocene species that died out would increase the species-loss percentage by some 5%. If threatened vertebrate species were to actually go extinct, losses would rise to between 14 and 40%, depending on the group. Such observations highlight that, although many species have already had their populations drastically reduced to near-critical levels, the Sixth Mass Extinction has not yet progressed to the point where it is unavoidable. Put another way, the vast majority of species that have occupied the world in concert with Homo sapiens are still alive and are possible to save. That task, however, will require slowing the abnormally high extinction rates that are now in progress, which in turn requires unified efforts to cap human population growth, decrease the average human footprint, reduce fossil fuel use while simultaneously increasing clean energy technologies, integrate

Coprolites reveal ecological interactions lost with the extinction of New Zealand birds.

Science.gov (United States)

Boast, Alexander P; Weyrich, Laura S; Wood, Jamie R; Metcalf, Jessica L; Knight, Rob; Cooper, Alan

2018-02-13

Over the past 50,000 y, biotic extinctions and declines have left a legacy of vacant niches and broken ecological interactions across global terrestrial ecosystems. Reconstructing the natural, unmodified ecosystems that preceded these events relies on high-resolution analyses of paleoecological deposits. Coprolites are a source of uniquely detailed information about trophic interactions and the behaviors, gut parasite communities, and microbiotas of prehistoric animal species. Such insights are critical for understanding the legacy effects of extinctions on ecosystems, and can help guide contemporary conservation and ecosystem restoration efforts. Here we use high-throughput sequencing (HTS) of ancient eukaryotic DNA from coprolites to reconstruct aspects of the biology and ecology of four species of extinct moa and the critically endangered kakapo parrot from New Zealand (NZ). Importantly, we provide evidence that moa and prehistoric kakapo consumed ectomycorrhizal fungi, suggesting these birds played a role in dispersing fungi that are key to NZ's natural forest ecosystems. We also provide the first DNA-based evidence that moa frequently supplemented their broad diets with ferns and mosses. Finally, we also find parasite taxa that provide insight into moa behavior, and present data supporting the hypothesis of coextinction between moa and several parasite species. Our study demonstrates that HTS sequencing of coprolites provides a powerful tool for resolving key aspects of ancient ecosystems and may rapidly provide information not obtainable by conventional paleoecological techniques, such as fossil analyses.

Body size reductions in nonmammalian eutheriodont therapsids (Synapsida) during the end-Permian mass extinction.

Science.gov (United States)

Huttenlocker, Adam K

2014-01-01

The extent to which mass extinctions influence body size evolution in major tetrapod clades is inadequately understood. For example, the 'Lilliput effect,' a common feature of mass extinctions, describes a temporary decrease in body sizes of survivor taxa in post-extinction faunas. However, its signature on existing patterns of body size evolution in tetrapods and the persistence of its impacts during post-extinction recoveries are virtually unknown, and rarely compared in both geologic and phylogenetic contexts. Here, I evaluate temporal and phylogenetic distributions of body size in Permo-Triassic therocephalian and cynodont therapsids (eutheriodonts) using a museum collections-based approach and time series model fitting on a regional stratigraphic sequence from the Karoo Basin, South Africa. I further employed rank order correlation tests on global age and clade rank data from an expanded phylogenetic dataset, and performed evolutionary model testing using Brownian (passive diffusion) models. Results support significant size reductions in the immediate aftermath of the end-Permian mass extinction (ca. 252.3 Ma) consistent with some definitions of Lilliput effects. However, this temporal succession reflects a pattern that was underscored largely by Brownian processes and constructive selectivity. Results also support two recent contentions about body size evolution and mass extinctions: 1) active, directional evolution in size traits is rare over macroevolutionary time scales and 2) geologically brief size reductions may be accomplished by the ecological removal of large-bodied species without rapid originations of new small-bodied clades or shifts from long-term evolutionary patterns.

A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids.

Science.gov (United States)

McGee, Matthew D; Borstein, Samuel R; Neches, Russell Y; Buescher, Heinz H; Seehausen, Ole; Wainwright, Peter C

2015-11-27

Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion. Copyright © 2015, American Association for the Advancement of Science.

["Hannibal ante portas" -- technical development and health care reorganization].

Science.gov (United States)

Fülesdi, Béla; Velkey, György

2011-11-20

Authors intend to analyze the impact of medical technical development on the Hungarian health care system and try to draw attention to potentially necessary measures for professional and structural health care reorganization.

Search for jet extinction in the inclusive jet-$p_T$ spectrum from proton-proton collisions at $\\sqrt{s}$ = 8 TeV

CERN Document Server

Khachatryan, Vardan; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Rabady, Dinyar; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; Bansal, Monika; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Knutsson, Albert; Luyckx, Sten; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Daci, Nadir; Heracleous, Natalie; Kalogeropoulos, Alexis; Keaveney, James; Kim, Tae Jeong; Lowette, Steven; Maes, Michael; Olbrechts, Annik; Python, Quentin; Strom, Derek; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Caillol, Cécile; Clerbaux, Barbara; De Lentdecker, Gilles; Dobur, Didar; Favart, Laurent; Gay, Arnaud; Grebenyuk, Anastasia; Léonard, Alexandre; Mohammadi, Abdollah; Perniè, Luca; Reis, Thomas; Seva, Tomislav; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Adler, Volker; Beernaert, Kelly; Benucci, Leonardo; Cimmino, Anna; Costantini, Silvia; Crucy, Shannon; Dildick, Sven; Fagot, Alexis; Garcia, Guillaume; Klein, Benjamin; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Ryckbosch, Dirk; Salva Diblen, Sinem; Sigamani, Michael; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Beluffi, Camille; Bruno, Giacomo; Castello, Roberto; Caudron, Adrien; Ceard, Ludivine; Da Silveira, Gustavo Gil; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Jez, Pavel; Komm, Matthias; Lemaitre, Vincent; Liao, Junhui; Nuttens, Claude; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Popov, Andrey; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Alves, Gilvan; Correa Martins Junior, Marcos; Dos Reis Martins, Thiago; Pol, Maria Elena; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Malbouisson, Helena; Malek, Magdalena; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santaolalla, Javier; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Vilela Pereira, Antonio; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Aleksandrov, Aleksandar; Genchev, Vladimir; Iaydjiev, Plamen; Marinov, Andrey; Piperov, Stefan; Rodozov, Mircho; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Hadjiiska, Roumyana; Kozhuharov, Venelin; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Du, Ran; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Plestina, Roko; Tao, Junquan; Wang, Xianyou; Wang, Zheng; Asawatangtrakuldee, Chayanit; Ban, Yong; Guo, Yifei; Li, Qiang; Li, Wenbo; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Zhang, Linlin; Zou, Wei; Avila, Carlos; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Kadija, Kreso; Luetic, Jelena; Mekterovic, Darko; Sudic, Lucija; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Bodlak, Martin; Finger, Miroslav; Finger Jr, Michael; Assran, Yasser; Elgammal, Sherif; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Murumaa, Marion; Raidal, Martti; Tiko, Andres; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Härkönen, Jaakko; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Peltola, Timo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Favaro, Carlotta; Ferri, Federico; Ganjour, Serguei; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Locci, Elizabeth; Malcles, Julie; Nayak, Aruna; Rander, John; Rosowsky, André; Titov, Maksym; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Charlot, Claude; Dahms, Torsten; Dalchenko, Mykhailo; Dobrzynski, Ludwik; Filipovic, Nicolas; Florent, Alice; Granier de Cassagnac, Raphael; Mastrolorenzo, Luca; Miné, Philippe; Mironov, Camelia; Naranjo, Ivo Nicolas; Nguyen, Matthew; Ochando, Christophe; Paganini, Pascal; Salerno, Roberto; Sauvan, Jean-Baptiste; Sirois, Yves; Veelken, Christian; Yilmaz, Yetkin; Zabi, Alexandre; Agram, Jean-Laurent; Andrea, Jeremy; Aubin, Alexandre; Bloch, Daniel; Brom, Jean-Marie; Chabert, Eric Christian; Collard, Caroline; Conte, Eric; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Goetzmann, Christophe; Le Bihan, Anne-Catherine; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Beaupere, Nicolas; Boudoul, Gaelle; Brochet, Sébastien; Carrillo Montoya, Camilo Andres; Chasserat, Julien; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; El Mamouni, Houmani; Fan, Jiawei; Fay, Jean; Gascon, Susan; Gouzevitch, Maxime; Ille, Bernard; Kurca, Tibor; Lethuillier, Morgan; Mirabito, Laurent; Perries, Stephane; Ruiz Alvarez, José David; Sabes, David; Sgandurra, Louis; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Xiao, Hong; Tsamalaidze, Zviad; Autermann, Christian; Beranek, Sarah; Bontenackels, Michael; Calpas, Betty; Edelhoff, Matthias; Feld, Lutz; Hindrichs, Otto; Klein, Katja; Ostapchuk, Andrey; Perieanu, Adrian; Raupach, Frank; Sammet, Jan; Schael, Stefan; Sprenger, Daniel; Weber, Hendrik; Wittmer, Bruno; Zhukov, Valery; Ata, Metin; Caudron, Julien; Dietz-Laursonn, Erik; Duchardt, Deborah; Erdmann, Martin; Fischer, Robert; Güth, Andreas; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Klingebiel, Dennis; Knutzen, Simon; Kreuzer, Peter; Merschmeyer, Markus; Meyer, Arnd; Olschewski, Mark; Padeken, Klaas; Papacz, Paul; Reithler, Hans; Schmitz, Stefan Antonius; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Weber, Martin; Cherepanov, Vladimir; Erdogan, Yusuf; Flügge, Günter; Geenen, Heiko; Geisler, Matthias; Haj Ahmad, Wael; Hoehle, Felix; Kargoll, Bastian; Kress, Thomas; Kuessel, Yvonne; Lingemann, Joschka; Nowack, Andreas; Nugent, Ian Michael; Perchalla, Lars; Pooth, Oliver; Stahl, Achim; Asin, Ivan; Bartosik, Nazar; Behr, Joerg; Behrenhoff, Wolf; Behrens, Ulf; Bell, Alan James; Bergholz, Matthias; Bethani, Agni; Borras, Kerstin; Burgmeier, Armin; Cakir, Altan; Calligaris, Luigi; Campbell, Alan; Choudhury, Somnath; Costanza, Francesco; Diez Pardos, Carmen; Dooling, Samantha; Dorland, Tyler; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Flucke, Gero; Garay Garcia, Jasone; Geiser, Achim; Gunnellini, Paolo; Hauk, Johannes; Hellwig, Gregor; Hempel, Maria; Horton, Dean; Jung, Hannes; Kasemann, Matthias; Katsas, Panagiotis; Kieseler, Jan; Kleinwort, Claus; Krücker, Dirk; Lange, Wolfgang; Leonard, Jessica; Lipka, Katerina; Lobanov, Artur; Lohmann, Wolfgang; Lutz, Benjamin; Mankel, Rainer; Marfin, Ihar; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mnich, Joachim; Mussgiller, Andreas; Naumann-Emme, Sebastian; Novgorodova, Olga; Nowak, Friederike; Ntomari, Eleni; Perrey, Hanno; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Ribeiro Cipriano, Pedro M; Ron, Elias; Sahin, Mehmet Özgür; Salfeld-Nebgen, Jakob; Saxena, Pooja; Schmidt, Ringo; Schoerner-Sadenius, Thomas; Schröder, Matthias; Spannagel, Simon; Vargas Trevino, Andrea Del Rocio; Walsh, Roberval; Wissing, Christoph; Aldaya Martin, Maria; Blobel, Volker; Centis Vignali, Matteo; Erfle, Joachim; Garutti, Erika; Goebel, Kristin; Görner, Martin; Gosselink, Martijn; Haller, Johannes; Höing, Rebekka Sophie; Kirschenmann, Henning; Klanner, Robert; Kogler, Roman; Lange, Jörn; Lapsien, Tobias; Lenz, Teresa; Marchesini, Ivan; Ott, Jochen; Peiffer, Thomas; Pietsch, Niklas; Rathjens, Denis; Sander, Christian; Schettler, Hannes; Schleper, Peter; Schlieckau, Eike; Schmidt, Alexander; Seidel, Markus; Poehlsen, Jennifer; Sola, Valentina; Stadie, Hartmut; Steinbrück, Georg; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Barth, Christian; Baus, Colin; Berger, Joram; Böser, Christian; Butz, Erik; Chwalek, Thorsten; De Boer, Wim; Descroix, Alexis; Dierlamm, Alexander; Feindt, Michael; Hartmann, Frank; Hauth, Thomas; Husemann, Ulrich; Katkov, Igor; Kornmayer, Andreas; Kuznetsova, Ekaterina; Lobelle Pardo, Patricia; Mozer, Matthias Ulrich; Müller, Thomas; Nürnberg, Andreas; Quast, Gunter; Rabbertz, Klaus; Ratnikov, Fedor; Röcker, Steffen; Simonis, Hans-Jürgen; Stober, Fred-Markus Helmut; Ulrich, Ralf; Wagner-Kuhr, Jeannine; Wayand, Stefan; Weiler, Thomas; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Markou, Athanasios; Markou, Christos; Psallidas, Andreas; Topsis-Giotis, Iasonas; Gouskos, Loukas; Panagiotou, Apostolos; Saoulidou, Niki; Stiliaris, Efstathios; Aslanoglou, Xenofon; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Bencze, Gyorgy; Hajdu, Csaba; Hidas, Pàl; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Molnar, Jozsef; Palinkas, Jozsef; Szillasi, Zoltan; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Swain, Sanjay Kumar; Beri, Suman Bala; Bhatnagar, Vipin; Dhingra, Nitish; Gupta, Ruchi; Kalsi, Amandeep Kaur; Kaur, Manjit; Mittal, Monika; Nishu, Nishu; Singh, Jasbir; Kumar, Ashok; Kumar, Arun; Ahuja, Sudha; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Varun; Banerjee, Sunanda; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dutta, Suchandra; Gomber, Bhawna; Jain, Sandhya; Jain, Shilpi; Khurana, Raman; Modak, Atanu; Mukherjee, Swagata; Roy, Debarati; Sarkar, Subir; Sharan, Manoj; Abdulsalam, Abdulla; Dutta, Dipanwita; Kailas, Swaminathan; Kumar, Vineet; Mohanty, Ajit Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Banerjee, Sudeshna; Chatterjee, Rajdeep Mohan; Dewanjee, Ram Krishna; Dugad, Shashikant; Ganguly, Sanmay; Ghosh, Saranya; Guchait, Monoranjan; Gurtu, Atul; Kole, Gouranga; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Mohanty, Gagan Bihari; Parida, Bibhuti; Sudhakar, Katta; Wickramage, Nadeesha; Bakhshiansohi, Hamed; Behnamian, Hadi; Etesami, Seyed Mohsen; Fahim, Ali; Goldouzian, Reza; Jafari, Abideh; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Barbone, Lucia; Calabria, Cesare; Chhibra, Simranjit Singh; Colaleo, Anna; Creanza, Donato; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Selvaggi, Giovanna; Silvestris, Lucia; Singh, Gurpreet; Venditti, Rosamaria; Verwilligen, Piet; Zito, Giuseppe; Abbiendi, Giovanni; Benvenuti, Alberto; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Primavera, Federica; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Travaglini, Riccardo; Albergo, Sebastiano; Cappello, Gigi; Chiorboli, Massimiliano; Costa, Salvatore; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Gallo, Elisabetta; Gonzi, Sandro; Gori, Valentina; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Sguazzoni, Giacomo; Tropiano, Antonio; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Ferro, Fabrizio; Lo Vetere, Maurizio; Robutti, Enrico; Tosi, Silvano; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Gerosa, Raffaele; Ghezzi, Alessio; Govoni, Pietro; Lucchini, Marco Toliman; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Martelli, Arabella; Marzocchi, Badder; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Ragazzi, Stefano; Redaelli, Nicola; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; Di Guida, Salvatore; Fabozzi, Francesco; Iorio, Alberto Orso Maria; Lista, Luca; Meola, Sabino; Merola, Mario; Paolucci, Pierluigi; Azzi, Patrizia; Bacchetta, Nicola; Bisello, Dario; Branca, Antonio; Carlin, Roberto; Dall'Osso, Martino; Dorigo, Tommaso; Galanti, Mario; Gasparini, Fabrizio; Giubilato, Piero; Gozzelino, Andrea; Kanishchev, Konstantin; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Montecassiano, Fabio; Passaseo, Marina; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Simonetto, Franco; Torassa, Ezio; Tosi, Mia; Vanini, Sara; Zotto, Pierluigi; Zucchetta, Alberto; Zumerle, Gianni; Gabusi, Michele; Ratti, Sergio P; Riccardi, Cristina; Salvini, Paola; Vitulo, Paolo; Biasini, Maurizio; Bilei, Gian Mario; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Mantovani, Giancarlo; Menichelli, Mauro; Romeo, Francesco; Saha, Anirban; Santocchia, Attilio; Spiezia, Aniello; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Broccolo, Giuseppe; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Donato, Silvio; Fiori, Francesco; Foà, Lorenzo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Moon, Chang-Seong; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Serban, Alin Titus; Spagnolo, Paolo; Squillacioti, Paola; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Vernieri, Caterina; Barone, Luciano; Cavallari, Francesca; Del Re, Daniele; Diemoz, Marcella; Grassi, Marco; Jorda, Clara; Longo, Egidio; Margaroli, Fabrizio; Meridiani, Paolo; Micheli, Francesco; Nourbakhsh, Shervin; Organtini, Giovanni; Paramatti, Riccardo; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Soffi, Livia; Traczyk, Piotr; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Casasso, Stefano; Costa, Marco; Degano, Alessandro; Demaria, Natale; Finco, Linda; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Musich, Marco; Obertino, Maria Margherita; Ortona, Giacomo; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Potenza, Alberto; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Solano, Ada; Staiano, Amedeo; Tamponi, Umberto; Belforte, Stefano; Candelise, Vieri; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Gobbo, Benigno; La Licata, Chiara; Marone, Matteo; Montanino, Damiana; Schizzi, Andrea; Umer, Tomo; Zanetti, Anna; Chang, Sunghyun; Kropivnitskaya, Anna; Nam, Soon-Kwon; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Kong, Dae Jung; Lee, Sangeun; Oh, Young Do; Park, Hyangkyu; Sakharov, Alexandre; Son, Dong-Chul; Kim, Jae Yool; Song, Sanghyeon; Choi, Suyong; Gyun, Dooyeon; Hong, Byung-Sik; Jo, Mihee; Kim, Hyunchul; Kim, Yongsun; Lee, Byounghoon; Lee, Kyong Sei; Park, Sung Keun; Roh, Youn; Choi, Minkyoo; Kim, Ji Hyun; Park, Inkyu; Park, Sangnam; Ryu, Geonmo; Ryu, Min Sang; Choi, Young-Il; Choi, Young Kyu; Goh, Junghwan; Kwon, Eunhyang; Lee, Jongseok; Seo, Hyunkwan; Yu, Intae; Juodagalvis, Andrius; Komaragiri, Jyothsna Rani; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-de La Cruz, Ivan; Lopez-Fernandez, Ricardo; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Vazquez Valencia, Fabiola; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Casimiro Linares, Edgar; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Reucroft, Steve; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Khalid, Shoaib; Khan, Wajid Ali; Khurshid, Taimoor; Shah, Mehar Ali; Shoaib, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Brona, Grzegorz; Bunkowski, Karol; Cwiok, Mikolaj; Dominik, Wojciech; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michał; Wolszczak, Weronika; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Karjavin, Vladimir; Konoplyanikov, Viktor; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Savina, Maria; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Zarubin, Anatoli; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Vorobyev, Andrey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Safronov, Grigory; Semenov, Sergey; Spiridonov, Alexander; Stolin, Viatcheslav; Vlasov, Evgueni; Zhokin, Alexander; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Mesyats, Gennady; Rusakov, Sergey V; Vinogradov, Alexey; Belyaev, Andrey; Boos, Edouard; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Lokhtin, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Tourtchanovitch, Leonid; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Dordevic, Milos; Ekmedzic, Marko; Milosevic, Jovan; Alcaraz Maestre, Juan; Battilana, Carlo; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Domínguez Vázquez, Daniel; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Merino, Gonzalo; Navarro De Martino, Eduardo; Pérez Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Albajar, Carmen; de Trocóniz, Jorge F; Missiroli, Marino; Brun, Hugues; Cuevas, Javier; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; Lloret Iglesias, Lara; Brochero Cifuentes, Javier Andres; Cabrillo, Iban Jose; Calderon, Alicia; Duarte Campderros, Jordi; Fernandez, Marcos; Gomez, Gervasio; Graziano, Alberto; Lopez Virto, Amparo; Marco, Jesus; Marco, Rafael; Martinez Rivero, Celso; Matorras, Francisco; Munoz Sanchez, Francisca Javiela; Piedra Gomez, Jonatan; Rodrigo, Teresa; Rodríguez-Marrero, Ana Yaiza; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Bachtis, Michail; Baillon, Paul; Ball, Austin; Barney, David; Benaglia, Andrea; Bendavid, Joshua; Benhabib, Lamia; Benitez, Jose F; Bernet, Colin; Bianchi, Giovanni; Bloch, Philippe; Bocci, Andrea; Bonato, Alessio; Bondu, Olivier; Botta, Cristina; Breuker, Horst; Camporesi, Tiziano; Cerminara, Gianluca; Christiansen, Tim; Colafranceschi, Stefano; D'Alfonso, Mariarosaria; D'Enterria, David; Dabrowski, Anne; David Tinoco Mendes, Andre; De Guio, Federico; De Roeck, Albert; De Visscher, Simon; Dobson, Marc; Dupont-Sagorin, Niels; Elliott-Peisert, Anna; Eugster, Jürg; Franzoni, Giovanni; Funk, Wolfgang; Giffels, Manuel; Gigi, Dominique; Gill, Karl; Giordano, Domenico; Girone, Maria; Glege, Frank; Guida, Roberto; Gundacker, Stefan; Guthoff, Moritz; Hammer, Josef; Hansen, Magnus; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Kousouris, Konstantinos; Krajczar, Krisztian; Lecoq, Paul; Lourenco, Carlos; Magini, Nicolo; Malgeri, Luca; Mannelli, Marcello; Masetti, Lorenzo; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; Moortgat, Filip; Morovic, Srecko; Mulders, Martijn; Musella, Pasquale; Orsini, Luciano; Pape, Luc; Perez, Emmanuelle; Perrozzi, Luca; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Pimiä, Martti; Piparo, Danilo; Plagge, Michael; Racz, Attila; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Sekmen, Sezen; Sharma, Archana; Siegrist, Patrice; Silva, Pedro; Simon, Michal; Sphicas, Paraskevas; Spiga, Daniele; Steggemann, Jan; Stieger, Benjamin; Stoye, Markus; Treille, Daniel; Tsirou, Andromachi; Veres, Gabor Istvan; Vlimant, Jean-Roch; Wardle, Nicholas; Wöhri, Hermine Katharina; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; König, Stefan; Kotlinski, Danek; Langenegger, Urs; Renker, Dieter; Rohe, Tilman; Bachmair, Felix; Bäni, Lukas; Bianchini, Lorenzo; Bortignon, Pierluigi; Buchmann, Marco-Andrea; Casal, Bruno; Chanon, Nicolas; Deisher, Amanda; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Dünser, Marc; Eller, Philipp; Grab, Christoph; Hits, Dmitry; Lustermann, Werner; Mangano, Boris; Marini, Andrea Carlo; Martinez Ruiz del Arbol, Pablo; Meister, Daniel; Mohr, Niklas; Nägeli, Christoph; Nef, Pascal; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pauss, Felicitas; Peruzzi, Marco; Quittnat, Milena; Rebane, Liis; Ronga, Frederic Jean; Rossini, Marco; Starodumov, Andrei; Takahashi, Maiko; 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Sharma, Seema; Soha, Aron; Spalding, William J; Spiegel, Leonard; Taylor, Lucas; Tkaczyk, Slawek; Tran, Nhan Viet; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vidal, Richard; Whitbeck, Andrew; Whitmore, Juliana; Yang, Fan; Acosta, Darin; Avery, Paul; Bourilkov, Dimitri; Carver, Matthew; Cheng, Tongguang; Curry, David; Das, Souvik; De Gruttola, Michele; Di Giovanni, Gian Piero; Field, Richard D; Fisher, Matthew; Furic, Ivan-Kresimir; Hugon, Justin; Konigsberg, Jacobo; Korytov, Andrey; Kypreos, Theodore; Low, Jia Fu; Matchev, Konstantin; Milenovic, Predrag; Mitselmakher, Guenakh; Muniz, Lana; Rinkevicius, Aurelijus; Shchutska, Lesya; Skhirtladze, Nikoloz; Snowball, Matthew; Yelton, John; Zakaria, Mohammed; Gaultney, Vanessa; Hewamanage, Samantha; Linn, Stephan; Markowitz, Pete; Martinez, German; Rodriguez, Jorge Luis; Adams, Todd; Askew, Andrew; Bochenek, Joseph; Diamond, Brendan; Haas, Jeff; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Prosper, Harrison; Veeraraghavan, Venkatesh; 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Schmitt, Michael Henry; Stoynev, Stoyan; Sung, Kevin; Velasco, Mayda; Won, Steven; Brinkerhoff, Andrew; Chan, Kwok Ming; Drozdetskiy, Alexey; Hildreth, Michael; Jessop, Colin; Karmgard, Daniel John; Kellams, Nathan; Lannon, Kevin; Luo, Wuming; Lynch, Sean; Marinelli, Nancy; Pearson, Tessa; Planer, Michael; Ruchti, Randy; Valls, Nil; Wayne, Mitchell; Wolf, Matthias; Woodard, Anna; Antonelli, Louis; Brinson, Jessica; Bylsma, Ben; Durkin, Lloyd Stanley; Flowers, Sean; Hill, Christopher; Hughes, Richard; Kotov, Khristian; Ling, Ta-Yung; Puigh, Darren; Rodenburg, Marissa; Smith, Geoffrey; Vuosalo, Carl; Winer, Brian L; Wolfe, Homer; Wulsin, Howard Wells; Berry, Edmund; Driga, Olga; Elmer, Peter; Hebda, Philip; Hunt, Adam; Koay, Sue Ann; Lujan, Paul; Marlow, Daniel; Medvedeva, Tatiana; Mooney, Michael; Olsen, James; Piroué, Pierre; Quan, Xiaohang; Saka, Halil; Stickland, David; Tully, Christopher; Werner, Jeremy Scott; Zenz, Seth Conrad; Zuranski, Andrzej; Brownson, Eric; Mendez, Hector; Ramirez Vargas, Juan Eduardo; Alagoz, Enver; Barnes, Virgil E; Benedetti, Daniele; Bolla, Gino; Bortoletto, Daniela; De Mattia, Marco; Everett, Adam; Hu, Zhen; Jha, Manoj; Jones, Matthew; Jung, Kurt; Kress, Matthew; Leonardo, Nuno; Lopes Pegna, David; Maroussov, Vassili; Merkel, Petra; Miller, David Harry; Neumeister, Norbert; Radburn-Smith, Benjamin Charles; Shipsey, Ian; Silvers, David; Svyatkovskiy, Alexey; Wang, Fuqiang; Xie, Wei; Xu, Lingshan; Yoo, Hwi Dong; Zablocki, Jakub; Zheng, Yu; Parashar, Neeti; Stupak, John; Adair, Antony; Akgun, Bora; Ecklund, Karl Matthew; Geurts, Frank JM; Li, Wei; Michlin, Benjamin; Padley, Brian Paul; Redjimi, Radia; Roberts, Jay; Zabel, James; Betchart, Burton; Bodek, Arie; Covarelli, Roberto; de Barbaro, Pawel; Demina, Regina; Eshaq, Yossof; Ferbel, Thomas; Garcia-Bellido, Aran; Goldenzweig, Pablo; Han, Jiyeon; Harel, Amnon; Khukhunaishvili, Aleko; Miner, Daniel Carl; Petrillo, Gianluca; Vishnevskiy, Dmitry; Ciesielski, Robert; Demortier, Luc; Goulianos, Konstantin; Lungu, Gheorghe; Mesropian, Christina; Arora, Sanjay; Barker, Anthony; Chou, John Paul; Contreras-Campana, Christian; Contreras-Campana, Emmanuel; Duggan, Daniel; Ferencek, Dinko; Gershtein, Yuri; Gray, Richard; Halkiadakis, Eva; Hidas, Dean; Lath, Amitabh; Panwalkar, Shruti; Park, Michael; Patel, Rishi; Rekovic, Vladimir; Salur, Sevil; Schnetzer, Steve; Seitz, Claudia; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Rose, Keith; Spanier, Stefan; York, Andrew; Bouhali, Othmane; Eusebi, Ricardo; Flanagan, Will; Gilmore, Jason; Kamon, Teruki; Khotilovich, Vadim; Krutelyov, Vyacheslav; Montalvo, Roy; Osipenkov, Ilya; Pakhotin, Yuriy; Perloff, Alexx; Roe, Jeffrey; Rose, Anthony; Safonov, Alexei; Sakuma, Tai; Suarez, Indara; Tatarinov, Aysen; Akchurin, Nural; Cowden, Christopher; Damgov, Jordan; Dragoiu, Cosmin; Dudero, Phillip Russell; Faulkner, James; Kovitanggoon, Kittikul; Kunori, Shuichi; Lee, Sung Won; Libeiro, Terence; Volobouev, Igor; Appelt, Eric; Delannoy, Andrés G; Greene, Senta; Gurrola, Alfredo; Johns, Willard; Maguire, Charles; Mao, Yaxian; Melo, Andrew; Sharma, Monika; Sheldon, Paul; Snook, Benjamin; Tuo, Shengquan; Velkovska, Julia; Arenton, Michael Wayne; Boutle, Sarah; Cox, Bradley; Francis, Brian; Goodell, Joseph; Hirosky, Robert; Ledovskoy, Alexander; Li, Hengne; Lin, Chuanzhe; Neu, Christopher; Wood, John; Gollapinni, Sowjanya; Harr, Robert; Karchin, Paul Edmund; Kottachchi Kankanamge Don, Chamath; Lamichhane, Pramod; Belknap, Donald; Carlsmith, Duncan; Cepeda, Maria; Dasu, Sridhara; Duric, Senka; Friis, Evan; Hall-Wilton, Richard; Herndon, Matthew; Hervé, Alain; Klabbers, Pamela; Klukas, Jeffrey; Lanaro, Armando; Lazaridis, Christos; Levine, Aaron; Loveless, Richard; Mohapatra, Ajit; Ojalvo, Isabel; Perry, Thomas; Pierro, Giuseppe Antonio; Polese, Giovanni; Ross, Ian; Sarangi, Tapas; Savin, Alexander; Smith, Wesley H; Woods, Nathaniel

2014-08-18

The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7 inverse-femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale.

Genetic sex determination and extinction.

Science.gov (United States)

Hedrick, Philip W; Gadau, Jürgen; Page, Robert E

2006-02-01

Genetic factors can affect the probability of extinction either by increasing the effect of detrimental variants or by decreasing the potential for future adaptive responses. In a recent paper, Zayed and Packer demonstrate that low variation at a specific locus, the complementary sex determination (csd) locus in Hymenoptera (ants, bees and wasps), can result in a sharply increased probability of extinction. Their findings illustrate situations in which there is a feedback process between decreased genetic variation at the csd locus owing to genetic drift and decreased population growth, resulting in an extreme type of extinction vortex for these ecologically important organisms.

Are marine and nonmarine extinctions correlated?

Science.gov (United States)

Rampino, Michael R.

Recent papers in Eos have debated the possible relationships between marine mass extinctions, comet showers, and volcanism [Alvarez, 1986; Officer and Grieve, 1986], and ail three might be linked [Rampino, 1987]. Moreover, as Officer and Grieve [ 1986] point out, various other causes have been suggested for given extinction events, including changes in climate, ocean circulation, and sea level fluctuations, possibly related to plate tectonics and continental positions. Also under debate is the issue of whether mass extinctions were gradual, stepped, or geologically sudden events (see, for example, Hut et al. [1987]). A missing ingredient thus far in these debates has been the record of faunal diversity of nonmarine animals. Does this show any agreement with the marine extinction record?

How does climate change cause extinction?

Science.gov (United States)

Cahill, Abigail E; Aiello-Lammens, Matthew E; Fisher-Reid, M Caitlin; Hua, Xia; Karanewsky, Caitlin J; Ryu, Hae Yeong; Sbeglia, Gena C; Spagnolo, Fabrizio; Waldron, John B; Warsi, Omar; Wiens, John J

2013-01-07

Anthropogenic climate change is predicted to be a major cause of species extinctions in the next 100 years. But what will actually cause these extinctions? For example, will it be limited physiological tolerance to high temperatures, changing biotic interactions or other factors? Here, we systematically review the proximate causes of climate-change related extinctions and their empirical support. We find 136 case studies of climatic impacts that are potentially relevant to this topic. However, only seven identified proximate causes of demonstrated local extinctions due to anthropogenic climate change. Among these seven studies, the proximate causes vary widely. Surprisingly, none show a straightforward relationship between local extinction and limited tolerances to high temperature. Instead, many studies implicate species interactions as an important proximate cause, especially decreases in food availability. We find very similar patterns in studies showing decreases in abundance associated with climate change, and in those studies showing impacts of climatic oscillations. Collectively, these results highlight our disturbingly limited knowledge of this crucial issue but also support the idea that changing species interactions are an important cause of documented population declines and extinctions related to climate change. Finally, we briefly outline general research strategies for identifying these proximate causes in future studies.

Recovery after mass extinction: evolutionary assembly in large-scale biosphere dynamics.

Science.gov (United States)

Solé, Ricard V; Montoya, José M; Erwin, Douglas H

2002-01-01

Biotic recoveries following mass extinctions are characterized by a process in which whole ecologies are reconstructed from low-diversity systems, often characterized by opportunistic groups. The recovery process provides an unexpected window to ecosystem dynamics. In many aspects, recovery is very similar to ecological succession, but important differences are also apparently linked to the innovative patterns of niche construction observed in the fossil record. In this paper, we analyse the similarities and differences between ecological succession and evolutionary recovery to provide a preliminary ecological theory of recoveries. A simple evolutionary model with three trophic levels is presented, and its properties (closely resembling those observed in the fossil record) are compared with characteristic patterns of ecological response to disturbances in continuous models of three-level ecosystems. PMID:12079530

Visible and ultraviolet (800--130 nm) extinction of vapor-condensed silicate, carbon, and silicon carbide smokes and the interstellar extinction curve

International Nuclear Information System (INIS)

Stephens, J.R.

1980-01-01

The extinction curves from 800 to 130 nm (1.25--7.7 μm -1 ) of amorphous silicate smokes nominally of olivine and pyroxene composition, carbon smokes, and crystalline SiC smokes are presented. The SiC smoke occurred in the low-temperature (β) cubic structural form. The mean grain radius ranged from 5 to 13 nm. The extinction profiles of the amorphous olivine smokes were similar in the ultraviolet to the measured extinction curves of crystalline olivine of nearly the same grain size. The SiC smoke showed an absorption edge which occurred at significantly longer wavelengths than the calculated extinction profile of the hexagonal SiC form previously used to calculate the interstellar extinction profile. Neither SiC nor amorphous silicates show an extinction band similar to the observed 6.6 μm -1 astronomical extinction band

Global extinction in spiral galaxies

NARCIS (Netherlands)

Tully, RB; Pierce, MJ; Saunders, W; Verheijen, MAW; Witchalls, PL

Magnitude-limited samples of spiral galaxies drawn from the Ursa Major and Pisces Clusters are used to determine their extinction properties as a function of inclination. Imaging photometry is available for 87 spirals in the B, R, I, and K' bands. Extinction causes systematic scatter in

DEEP NEAR-INFRARED SURVEY OF THE PIPE NEBULA. II. DATA, METHODS, AND DUST EXTINCTION MAPS

International Nuclear Information System (INIS)

Roman-Zuniga, Carlos G.; Alves, Joao F.; Lada, Charles J.; Lombardi, Marco

2010-01-01

We present a new set of high-resolution dust extinction maps of the nearby and essentially starless Pipe Nebula molecular cloud. The maps were constructed from a concerted deep near-infrared imaging survey with the ESO-VLT, ESO-NTT, CAHA 3.5 m telescopes, and 2MASS data. The new maps have a resolution three times higher than the previous extinction map of this cloud by Lombardi et al. and are able to resolve structures down to 2600 AU. We detect 244 significant extinction peaks across the cloud. These peaks have masses between 0.1 and 18.4 M sun , diameters between 1.2 and 5.7 x 10 4 AU (0.06 and 0.28 pc), and mean densities of about 10 4 cm -3 , all in good agreement with previous results. From the analysis of the mean surface density of companions we find a well-defined scale near 1.4 x 10 4 AU below which we detect a significant decrease in structure of the cloud. This scale is smaller than the Jeans length calculated from the mean density of the peaks. The surface density of peaks is not uniform but instead it displays clustering. Extinction peaks in the Pipe Nebula appear to have a spatial distribution similar to the stars in Taurus, suggesting that the spatial distribution of stars evolves directly from the primordial spatial distribution of high-density material.

Methylphenidate enhances extinction of contextual fear

OpenAIRE

Abraham, Antony D.; Cunningham, Christopher L.; Lattal, K. Matthew

2012-01-01

Methylphenidate (MPH, Ritalin) is a norepinephrine and dopamine transporter blocker that is widely used in humans for treatment of attention deficit disorder and narcolepsy. Although there is some evidence that targeted microinjections of MPH may enhance fear acquisition, little is known about the effect of MPH on fear extinction. Here, we show that MPH, administered before or immediately following extinction of contextual fear, will enhance extinction retention in C57BL/6 mice. Animals that ...

One extinct turtle species less: Pelusios seychellensis is not extinct, it never existed.

Directory of Open Access Journals (Sweden)

Heiko Stuckas

Full Text Available Pelusios seychellensis is thought to be a freshwater turtle species endemic to the island of Mahé, Seychelles. There are only three museum specimens from the late 19(th century known. The species has been never found again, despite intensive searches on Mahé. Therefore, P. seychellensis has been declared as "Extinct" by the IUCN and is the sole putatively extinct freshwater turtle species. Using DNA sequences of three mitochondrial genes of the historical type specimen and phylogenetic analyses including all other species of the genus, we provide evidence that the description of P. seychellensis was erroneously based on a widely distributed West African species, P. castaneus. Consequently, we synonymize the two species and delete P. seychellensis from the list of extinct chelonian species and from the faunal list of the Seychelles.

EXTINCTION AND DUST GEOMETRY IN M83 H II REGIONS: AN HUBBLE SPACE TELESCOPE/WFC3 STUDY

Energy Technology Data Exchange (ETDEWEB)

Liu, Guilin; Calzetti, Daniela; Hong, Sungryong [Astronomy Department, University of Massachusetts, Amherst, MA 01003 (United States); Whitmore, Bradley [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Chandar, Rupali [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); O' Connell, Robert W. [Astronomy Department, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903 (United States); Blair, William P. [Center for Astrophysical Sciences, Johns Hopkins University, Baltimore, MD 21218 (United States); Cohen, Seth H.; Kim, Hwihyun [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Frogel, Jay A., E-mail: liu@pha.jhu.edu [Galaxies Unlimited, Lutherville, MD 21093 (United States)

2013-12-01

We present Hubble Space Telescope/WFC3 narrow-band imaging of the starburst galaxy M83 targeting the hydrogen recombination lines (Hβ, Hα, and Paβ), which we use to investigate the dust extinction in the H II regions. We derive extinction maps with 6 pc spatial resolution from two combinations of hydrogen lines (Hα/Hβ and Hα/Paβ), and show that the longer wavelengths probe larger optical depths, with A{sub V} values larger by ≳1 mag than those derived from the shorter wavelengths. This difference leads to a factor ≳2 discrepancy in the extinction-corrected Hα luminosity, a significant effect when studying extragalactic H II regions. By comparing these observations to a series of simple models, we conclude that a large diversity of absorber/emitter geometric configurations can account for the data, implying a more complex physical structure than the classical foreground ''dust screen'' assumption. However, most data points are bracketed by the foreground screen and a model where dust and emitters are uniformly mixed. When averaged over large (≳100-200 pc) scales, the extinction becomes consistent with a ''dust screen'', suggesting that other geometries tend to be restricted to more local scales. Moreover, the extinction in any region can be described by a combination of the foreground screen and the uniform mixture model with weights of 1/3 and 2/3 in the center (≲2 kpc), respectively, and 2/3 and 1/3 for the rest of the disk. This simple prescription significantly improves the accuracy of the dust extinction corrections and can be especially useful for pixel-based analyses of galaxies similar to M83.

Workplace Re-organization and Changes in Physiological Stress Markers

DEFF Research Database (Denmark)

Carlsson, Rikke Hinge; Hansen, Åse Marie; Kristiansen, Jesper

2014-01-01

The aim of this study was to investigate changes in physiological stress markers as a consequence of workplace reorganization. Moreover, we aimed to investigate changes in the psychosocial work environment (job strain, effortreward imbalance (ERI), in psychological distress (stress symptoms......, perceived stress) and the mediating effect of these factors on changes in physiological stress markers. We used data from a longitudinal study that studied the health consequences of a major reorganization of non-state public offices executed in Denmark on 1 January 2007. Collection of clinical...... and questionnaire data was in 2006 and 2008, and in this sub-study we included 359 participants. To reflect stress reactions of the autonomic nervous system, the endocrine system and the immune system, we included 13 physiological markers. We observed significant change in several physiological stress markers...

Bilateral reorganization of the dentate gyrus in hippocampal sclerosis: a postmortem study.

Science.gov (United States)

Thom, M; Martinian, L; Catarino, C; Yogarajah, M; Koepp, M J; Caboclo, L; Sisodiya, S M

2009-09-29

Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.

Interstellar extinction in the Large Magellanic Cloud

International Nuclear Information System (INIS)

Nandy, K.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.; Houziaux, L.

1980-01-01

Recent UV observations together with complementary visible data of several reddened and comparison stars of similar spectral types in the Large Magellanic Cloud have been used to study the interstellar extinction in that galaxy. Most of the reddened stars studied here are located within 2 0 of 30 Doradus and show remarkably high extinction in the far UV, suggesting a large abundance of small particles. From the optical wavelength to 2,600 A the normalised extinction curves of the LMC stars are similar to the mean galactic extinction law. (author)

Mass extinctions vs. uniformitarianism in biological evolution

Energy Technology Data Exchange (ETDEWEB)

Bak, P.; Paczuski, M.

1995-12-31

It is usually believed that Darwin`s theory leads to a smooth gradual evolution, so that mass extinctions must be caused by external shocks. However, it has recently been argued that mass extinctions arise from the intrinsic dynamics of Darwinian evolution. Species become extinct when swept by intermittent avalanches propagating through the global ecology. These ideas are made concrete through studies of simple mathematical models of co-evolving species. The models exhibit self-organized criticality and describe some general features of the extinction pattern in the fossil record.

Further Evidence of Auditory Extinction in Aphasia

Science.gov (United States)

Marshall, Rebecca Shisler; Basilakos, Alexandra; Love-Myers, Kim

2013-01-01

Purpose: Preliminary research ( Shisler, 2005) suggests that auditory extinction in individuals with aphasia (IWA) may be connected to binding and attention. In this study, the authors expanded on previous findings on auditory extinction to determine the source of extinction deficits in IWA. Method: Seventeen IWA (M[subscript age] = 53.19 years)…

Reactivated Memories Compete for Expression After Pavlovian Extinction

Science.gov (United States)

Laborda, Mario A.; Miller, Ralph R.

2012-01-01

We view the response decrement resulting from extinction treatment as an interference effect, in which the reactivated memory from acquisition competes with the reactivated memory from extinction for behavioral expression. For each of these memories, reactivation is proportional to both the strength of the stimulus-outcome association and the quality of the facilitatory cues for that association which are present at test. Here we review basic extinction and recovery-from-extinction phenomena, showing how these effects are explicable in this associative interference framework. Moreover, this orientation has and continues to dictate efficient manipulations for minimizing recovery from extinction. This in turn suggests procedures that might reduce relapse from exposure therapy for a number of psychological disorders. Some of these manipulations enhance the facilitatory cues from extinction that are present at test, others strengthen the extinction association (i.e., CS-no outcome), and yet others seem to work by a combination of these two processes. PMID:22326812

Running from fear: Exercise modulation of fear extinction.

Science.gov (United States)

Tanner, Margaret K; Hake, Holly S; Bouchet, Courtney A; Greenwood, Benjamin N

2018-03-31

Extinction-based exposure therapy is the most common behavioral therapy for anxiety and trauma-related disorders, but fear tends to resurface even after successful extinction. Identification of novel strategies to enhance fear extinction and reduce fear relapse is of paramount importance to mental health. Exercise can enhance cognitive function, but it is not yet well understood whether exercise can be an effective augmentation strategy for fear extinction. In the current review, we present the current state of knowledge on the effects of exercise on fear extinction. Effects of exercise duration, explanations for conflicting results, and potential mechanisms, focusing on a hypothesized role for dopamine, are all discussed. We also provide new data suggesting that the timing in which acute exercise occurs relative to fear extinction, is a crucial variable in determining whether exercise can enhance fear extinction. Clinical implications and ideas to guide future research endeavors in this area are provided. Copyright © 2018 Elsevier Inc. All rights reserved.

Modeling vegetation heights from high resolution stereo aerial photography: an application for broad-scale rangeland monitoring.

Science.gov (United States)

Gillan, Jeffrey K; Karl, Jason W; Duniway, Michael; Elaksher, Ahmed

2014-11-01

Vertical vegetation structure in rangeland ecosystems can be a valuable indicator for assessing rangeland health and monitoring riparian areas, post-fire recovery, available forage for livestock, and wildlife habitat. Federal land management agencies are directed to monitor and manage rangelands at landscapes scales, but traditional field methods for measuring vegetation heights are often too costly and time consuming to apply at these broad scales. Most emerging remote sensing techniques capable of measuring surface and vegetation height (e.g., LiDAR or synthetic aperture radar) are often too expensive, and require specialized sensors. An alternative remote sensing approach that is potentially more practical for managers is to measure vegetation heights from digital stereo aerial photographs. As aerial photography is already commonly used for rangeland monitoring, acquiring it in stereo enables three-dimensional modeling and estimation of vegetation height. The purpose of this study was to test the feasibility and accuracy of estimating shrub heights from high-resolution (HR, 3-cm ground sampling distance) digital stereo-pair aerial images. Overlapping HR imagery was taken in March 2009 near Lake Mead, Nevada and 5-cm resolution digital surface models (DSMs) were created by photogrammetric methods (aerial triangulation, digital image matching) for twenty-six test plots. We compared the heights of individual shrubs and plot averages derived from the DSMs to field measurements. We found strong positive correlations between field and image measurements for several metrics. Individual shrub heights tended to be underestimated in the imagery, however, accuracy was higher for dense, compact shrubs compared with shrubs with thin branches. Plot averages of shrub height from DSMs were also strongly correlated to field measurements but consistently underestimated. Grasses and forbs were generally too small to be detected with the resolution of the DSMs. Estimates of

Atomic force microscopy observation of lipopolysaccharide-induced cardiomyocyte cytoskeleton reorganization.

Science.gov (United States)

Wang, Liqun; Chen, Tangting; Zhou, Xiang; Huang, Qiaobing; Jin, Chunhua

2013-08-01

We applied atomic force microscopy (AFM) to observe lipopolysaccharide (LPS)-induced intracellular cytoskeleton reorganization in primary cardiomyocytes from neonatal mouse. The nonionic detergent Triton X-100 was used to remove the membrane, soluble proteins, and organelles from the cell. The remaining cytoskeleton can then be directly visualized by AFM. Using three-dimensional technique of AFM, we were able to quantify the changes of cytoskeleton by the "density" and total "volume" of the cytoskeleton fibers. Compared to the control group, the density of cytoskeleton was remarkably decreased and the volume of cytoskeleton was significantly increased after LPS treatment, which suggests that LPS may induce the cytoskeleton reorganization and change the cardiomyocyte morphology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

Directory of Open Access Journals (Sweden)

Lea A Randall

Full Text Available A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2 and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

Science.gov (United States)

Randall, Lea A; Smith, Des H V; Jones, Breana L; Prescott, David R C; Moehrenschlager, Axel

2015-01-01

A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens) in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2) and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

A High Molar Extinction Coefficient Mono-Anthracenyl Bipyridyl Heteroleptic Ruthenium(II Complex: Synthesis, Photophysical and Electrochemical Properties

Directory of Open Access Journals (Sweden)

Peter A. Ajibade

2011-06-01

Full Text Available In our quest to develop good materials as photosensitizers for photovoltaic dye-sensitized solar cells (DSSCs, cis-dithiocyanato-4-(2,3-dimethylacrylic acid-2,2'-bipyridyl-4-(9-anthracenyl-(2,3-dimethylacrylic-2,2'-bipyridyl ruthenium(II complex, a high molar extinction coefficient charge transfer sensitizer, was designed, synthesized and characterized by spectroscopy and electrochemical techniques. Earlier studies on heteroleptic ruthenium(II complex analogues containing functionalized oligo-anthracenyl phenanthroline ligands have been reported and documented. Based on a general linear correlation between increase in the length of π-conjugation bond and the molar extinction coefficients, herein, we report the photophysical and electrochemical properties of a Ru(II bipyridyl complex analogue with a single functionalized anthracenyl unit. Interestingly, the complex shows better broad and intense metal-to ligand charge transfer (MLCT band absorption with higher molar extinction coefficient (λmax = 518 nm, e = 44900 M−1cm−1, and appreciable photoluminescence spanning the visible region than those containing higher anthracenyl units. It was shown that molar absorption coefficient of the complexes may not be solely depended on the extended π-conjugation but are reduced by molecular aggregation in the molecules.

Knowing the dense plasma focus - The coming of age (of the PF) with broad-ranging scaling laws

Science.gov (United States)

Saw, S. H.; Lee, S.

2017-03-01

The dense plasma focus is blessed not only with copious multi-radiations ranging from electron and ion beams, x-rays both soft and hard, fusion neutrons D-D and D-T but also with the property of enhanced compression from radiative collapse leading to HED (high energy density) states. The Lee code has been used in extensive systematic numerical experiments tied to reality through fitting with measured current waveforms and verified through comparison of measured and computed yields and measurements of multi-radiation. The studies have led to establishment of scaling laws with respect to storage energy, discharge current and pinch currents for fusion neutrons, characteristic soft x-rays, all-line radiation and ion beams. These are summarized here together with a first-time presentation of a scaling law of radiatively enhanced compression as a function of atomic number of operational gas. This paper emphasizes that such a broad range of scaling laws signals the coming of age of the DPF and presents a reference platform for planning the many potential applications such as in advanced SXR lithography, materials synthesizing and testing, medical isotopes, imaging and energy and high energy density (HED).

Extinction Generates Outcome-Specific Conditioned Inhibition.

Science.gov (United States)

Laurent, Vincent; Chieng, Billy; Balleine, Bernard W

2016-12-05

Extinction involves altering a previously established predictive relationship between a cue and its outcome by repeatedly presenting that cue alone. Although it is widely accepted that extinction generates some form of inhibitory learning [1-4], direct evidence for this claim has been lacking, and the nature of the associative changes induced by extinction have, therefore, remained a matter of debate [5-8]. In the current experiments, we used a novel behavioral approach that we recently developed and that provides a direct measure of conditioned inhibition [9] to compare the influence of extinguished and non-extinguished cues on choice between goal-directed actions. Using this approach, we provide direct evidence that extinction generates outcome-specific conditioned inhibition. Furthermore, we demonstrate that this inhibitory learning is controlled by the infralimbic cortex (IL); inactivation of the IL using M4 DREADDs abolished outcome-specific inhibition and rendered the cue excitatory. Importantly, we found that context modulated this inhibition. Outside its extinction context, the cue was excitatory and functioned as a specific predictor of its previously associated outcome, biasing choice toward actions earning the same outcome. In its extinction context, however, the cue acted as a specific inhibitor and biased choice toward actions earning different outcomes. Context modulation of these excitatory and inhibitory memories was mediated by the dorsal hippocampus (HPC), suggesting that the HPC and IL act in concert to control the influence of conditioned inhibitors on choice. These findings demonstrate for the first time that extinction turns a cue into a net inhibitor that can influence choice via counterfactual action-outcome associations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Patterns in Greater Sage-grouse population dynamics correspond with public grazing records at broad scales.

Science.gov (United States)

Monroe, Adrian P; Aldridge, Cameron L; Assal, Timothy J; Veblen, Kari E; Pyke, David A; Casazza, Michael L

2017-06-01

Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing across Wyoming, USA, and we used Greater Sage-grouse (Centrocercus urophasianus) as a model organism to evaluate responses to livestock management. With annual counts of male Sage-grouse from 743 leks (breeding display sites) during 2004-2014, we modeled population trends in response to grazing level (represented by a relative grazing index) and timing across a gradient in vegetation productivity as measured by the Normalized Vegetation Difference Index (NDVI). We found grazing can have both positive and negative effects on Sage-grouse populations depending on the timing and level of grazing. Sage-grouse populations responded positively to higher grazing levels after peak vegetation productivity, but populations declined when similar grazing levels occurred earlier, likely reflecting the sensitivity of cool-season grasses to grazing during peak growth periods. We also found support for the hypothesis that effects of grazing management vary with local vegetation productivity. These results illustrate the importance of broad-scale analyses by revealing patterns in Sage-grouse population trends that may not be inferred from studies at finer scales, and could inform sustainable grazing management in these ecosystems. © 2017 by the Ecological Society of America.

77 FR 55182 - Reorganization of Foreign-Trade Zone 151 Under Alternative Site Framework Findlay, Ohio

Science.gov (United States)

2012-09-07

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [Order No. 1855] Reorganization of Foreign-Trade... option for the establishment or reorganization of zones; Whereas, the Findlay/Hancock County Chamber of Commerce, grantee of Foreign-Trade Zone 151, submitted an application to the Board (FTZ Docket 20-2012...

Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

Directory of Open Access Journals (Sweden)

Sarah Boukezzi

2017-06-01

Full Text Available Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD. Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS during eye movement desensitization and reprocessing (EMDR therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to determine if these previous results found in animals can be reproduced in humans. Twenty-two healthy participants took part in a classical fear conditioning, extinction, and extinction recall paradigm. Behavioral responses (fear expectations as well as psychophysiological measures (skin conductance responses, SCRs were recorded. The results showed a significant fear expectation decrease during fear extinction with BLS. Additionally, SCR for fear extinction retrieval were significantly lower with BLS. Our results demonstrate the importance of BLS to reduce negative emotions, and provide a successful model to further explore the neural mechanisms underlying the sole BLS effect in the EMDR.

Body size reductions in nonmammalian eutheriodont therapsids (Synapsida during the end-Permian mass extinction.

Directory of Open Access Journals (Sweden)

Adam K Huttenlocker

Full Text Available The extent to which mass extinctions influence body size evolution in major tetrapod clades is inadequately understood. For example, the 'Lilliput effect,' a common feature of mass extinctions, describes a temporary decrease in body sizes of survivor taxa in post-extinction faunas. However, its signature on existing patterns of body size evolution in tetrapods and the persistence of its impacts during post-extinction recoveries are virtually unknown, and rarely compared in both geologic and phylogenetic contexts. Here, I evaluate temporal and phylogenetic distributions of body size in Permo-Triassic therocephalian and cynodont therapsids (eutheriodonts using a museum collections-based approach and time series model fitting on a regional stratigraphic sequence from the Karoo Basin, South Africa. I further employed rank order correlation tests on global age and clade rank data from an expanded phylogenetic dataset, and performed evolutionary model testing using Brownian (passive diffusion models. Results support significant size reductions in the immediate aftermath of the end-Permian mass extinction (ca. 252.3 Ma consistent with some definitions of Lilliput effects. However, this temporal succession reflects a pattern that was underscored largely by Brownian processes and constructive selectivity. Results also support two recent contentions about body size evolution and mass extinctions: 1 active, directional evolution in size traits is rare over macroevolutionary time scales and 2 geologically brief size reductions may be accomplished by the ecological removal of large-bodied species without rapid originations of new small-bodied clades or shifts from long-term evolutionary patterns.

Body Size Reductions in Nonmammalian Eutheriodont Therapsids (Synapsida) during the End-Permian Mass Extinction

Science.gov (United States)

Huttenlocker, Adam K.

2014-01-01

The extent to which mass extinctions influence body size evolution in major tetrapod clades is inadequately understood. For example, the ‘Lilliput effect,’ a common feature of mass extinctions, describes a temporary decrease in body sizes of survivor taxa in post-extinction faunas. However, its signature on existing patterns of body size evolution in tetrapods and the persistence of its impacts during post-extinction recoveries are virtually unknown, and rarely compared in both geologic and phylogenetic contexts. Here, I evaluate temporal and phylogenetic distributions of body size in Permo-Triassic therocephalian and cynodont therapsids (eutheriodonts) using a museum collections-based approach and time series model fitting on a regional stratigraphic sequence from the Karoo Basin, South Africa. I further employed rank order correlation tests on global age and clade rank data from an expanded phylogenetic dataset, and performed evolutionary model testing using Brownian (passive diffusion) models. Results support significant size reductions in the immediate aftermath of the end-Permian mass extinction (ca. 252.3 Ma) consistent with some definitions of Lilliput effects. However, this temporal succession reflects a pattern that was underscored largely by Brownian processes and constructive selectivity. Results also support two recent contentions about body size evolution and mass extinctions: 1) active, directional evolution in size traits is rare over macroevolutionary time scales and 2) geologically brief size reductions may be accomplished by the ecological removal of large-bodied species without rapid originations of new small-bodied clades or shifts from long-term evolutionary patterns. PMID:24498335

Bilateral Alternating Auditory Stimulations Facilitate Fear Extinction and Retrieval

OpenAIRE

Boukezzi, Sarah; Silva, Catarina; Nazarian, Bruno; Rousseau, Pierre-François; Guedj, Eric; Valenzuela-Moguillansky, Camila; Khalfa, Stéphanie

2017-01-01

Disruption of fear conditioning, its extinction and its retrieval are at the core of posttraumatic stress disorder (PTSD). Such deficits, especially fear extinction delay, disappear after alternating bilateral stimulations (BLS) during eye movement desensitization and reprocessing (EMDR) therapy. An animal model of fear recovery, based on auditory cued fear conditioning and extinction learning, recently showed that BLS facilitate fear extinction and fear extinction retrieval. Our goal was to ...

Honey bee forager thoracic temperature inside the nest is tuned to broad-scale differences in recruitment motivation.

Science.gov (United States)

Sadler, Nik; Nieh, James C

2011-02-01

Insects that regulate flight muscle temperatures serve as crucial pollinators in a broad range of ecosystems, in part because they forage over a wide span of temperatures. Honey bees are a classic example and maintain their thoracic muscles at temperatures (T(th)) tuned to the caloric benefits of floral resources. Using infrared thermography, we tested the hypothesis that forager motivation to recruit nestmates for a food source is positively correlated with T(th). We trained bees to a sucrose feeder located 5-100 m from the nest. Recruiting foragers had a significantly higher average T(th) (2.7°C higher) when returning from 2.5 mol l(-1) sucrose (65% w/w) than when returning from 1.0 mol l(-1) sucrose (31% w/w). Foragers exhibited significantly larger thermal fluctuations the longer they spent inside the nest between foraging trips. The difference between maximum and minimum temperatures during a nest visit (T(range)) increased with total duration of the nest visit (0.7°C increase per additional min spent inside the nest). Bees that recruited nestmates (waggle or round danced) were significantly warmer, with a 1.4-1.5 times higher ΔT(th) (difference between T(th) and nest ambient air temperature) than bees who tremble danced or simply walked on the nest floor without recruiting between foraging bouts. However, recruiter T(th) was not correlated with finer-scale measures of motivation: the number of waggle dance circuits or waggle dance return phase duration. These results support the hypothesis that forager T(th) within the nest is correlated to broad-scale differences in foraging motivation.

Mass Extinctions and Supernova Explosions

Science.gov (United States)

Korschinek, Gunther

A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation or the direct exposure of lethal X-rays. Another indirect effect is cloud formation, induced by cosmic rays in the atmosphere which result in a drop in the Earth's temperature, causing major glaciations of the Earth. The discovery of highly intensive gamma-ray bursts (GRBs), which could be connected to SNe, initiated further discussions on possible life-threatening events in the Earth's history. The probability that GRBs hit the Earth is very low. Nevertheless, a past interaction of Earth with GRBs and/or SNe cannot be excluded and might even have been responsible for past extinction events.

High frequency of functional extinctions in ecological networks.

Science.gov (United States)

Säterberg, Torbjörn; Sellman, Stefan; Ebenman, Bo

2013-07-25

Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species. There is a growing concern that this might cause critical abundance thresholds of species to be crossed, with extinction cascades and state shifts in ecosystems as a consequence. When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems, their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species' ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence.

Reorganization of a hospital catering system increases food intake in patients with inadequate intake

DEFF Research Database (Denmark)

Freil, M; Nielsen, MA; Blitz, B

2006-01-01

Background : Low food intake is a frequent problem in undernourished hospital patients. Objective: To study whether a reorganization of a hospital catering system enabling patients to choose their evening meal individually, in combination with an increase in the energy density of the food....... Conclusions: Reorganization of a hospital catering system can increase energy and protein intake and reduce waste substantially....

Interstellar Silicon Depletion and the Ultraviolet Extinction

Science.gov (United States)

Mishra, Ajay; Li, Aigen

2018-01-01

Spinning small silicate grains were recently invoked to account for the Galactic foreground anomalous microwave emission. These grains, if present, will absorb starlight in the far ultraviolet (UV). There is also renewed interest in attributing the enigmatic 2175 Å interstellar extinction bump to small silicates. To probe the role of silicon in the UV extinction, we explore the relations between the amount of silicon required to be locked up in silicates [Si/H]dust and the 2175 Å bump or the far-UV extinction rise, based on an analysis of the extinction curves along 46 Galactic sightlines for which the gas-phase silicon abundance [Si/H]gas is known. We derive [Si/H]dust either from [Si/H]ISM - [Si/H]gas or from the Kramers- Kronig relation which relates the wavelength-integrated extinction to the total dust volume, where [Si/H]ISM is the interstellar silicon reference abundance and taken to be that of proto-Sun or B stars. We also derive [Si/H]dust from fi�tting the observed extinction curves with a mixture of amorphous silicates and graphitic grains. We fi�nd that in all three cases [Si/H]dust shows no correlation with the 2175 Å bump, while the carbon depletion [C/H]dust tends to correlate with the 2175 Å bump. This supports carbon grains instead of silicates as the possible carrier of the 2175 Å bump. We also �find that neither [Si/H]dust nor [C/H]dust alone correlates with the far-UV extinction, suggesting that the far-UV extinction is a combined effect of small carbon grains and silicates.

Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate.

Directory of Open Access Journals (Sweden)

Paulo R Guimarães

Full Text Available BACKGROUND: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3 kg, yet these dispersers were extinct in South America 10-15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. METHODOLOGY/PRINCIPAL FINDINGS: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4-10 cm in diameter with up to five large seeds, and fruits > 10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size with either a single or few ( 100 seeds. Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness. CONCLUSIONS/SIGNIFICANCE: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among

Reorganization of Dentate Gyrus Microcircuits During Epileptogenesis

OpenAIRE

Jones, Ryan Thomas

2014-01-01

Temporal lobe epilepsy (TLE) is a form of acquired epilepsy characterized by recurrent and unprovoked seizures. TLE often develops following a precipitating neurological insult, such as traumatic brain injury, stroke, infection, prolonged febrile seizures or status epilepticus. These insults can initiate a constellation of genetic, functional, network and systems level reorganization that transforms a normal non-epileptic brain into one capable of generating recurrent and unprovoked seizures....

The extinction of the West African lion: whose responsibility?

NARCIS (Netherlands)

Nollkaemper, A.

2014-01-01

A recently published study showed that the lion in West Africa is now critically endangered and faces extinction. From one angle, this would be just one of the large (though unknown) number of species that has previously faced extinction or has even become extinct. But the risk of extinction of some

Observations of interstellar ultraviolet extinction from the S2/68 experiment in the TD-1 satellite

International Nuclear Information System (INIS)

Nandy, K.; Thompson, G.I.; Carnochan, D.J.; Wilson, R.

1978-01-01

The galactic distribution of the agents which cause the extinction bump near 2200 A and the ultraviolet colour excess E(1550-2740) within 2 kpc of the Sun in the galactic plane have been studied from the observations obtained with the S2/68 experiment in the TD-1 satellite. The mean reddening-distance relation in the galactic plane has been obtained for different longitudes. The study of the extinction parameter with galactic latitude shows a strong concentration of the dust towards the galactic plane with a scale height of 110 pc. (author)

Brain structural connectivity and context-dependent extinction memory.

Science.gov (United States)

Hermann, Andrea; Stark, Rudolf; Blecker, Carlo R; Milad, Mohammed R; Merz, Christian J

2017-08-01

Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity. Diffusion-tensor imaging was used to determine the fractional anisotropy as a measure of white matter structural integrity of fiber tracts connecting central brain regions of the fear and extinction circuit (uncinate fasciculus, cingulum). Forty-five healthy men participated in a two-day fear conditioning experiment with fear acquisition in context A and extinction learning in context B on the first day. Extinction recall in the extinction context as well as renewal in the acquisition context and a novel context C took place one day later. Renewal of conditioned fear (skin conductance responses) in the acquisition context was associated with higher structural integrity of the hippocampal part of the cingulum. Enhanced structural integrity of the cingulum might be related to stronger hippocampal modulation of the dorsal anterior cingulate cortex, a region important for modulating conditioned fear output by excitatory projections to the amygdala. This finding underpins the crucial role of individual differences in the structural integrity of relevant fiber tracts for context-dependent extinction recall and return of fear after exposure therapy in anxiety disorders. © 2017 Wiley Periodicals, Inc.

The Sixth Great Mass Extinction

Science.gov (United States)

Wagler, Ron

2012-01-01

Five past great mass extinctions have occurred during Earth's history. Humanity is currently in the midst of a sixth, human-induced great mass extinction of plant and animal life (e.g., Alroy 2008; Jackson 2008; Lewis 2006; McDaniel and Borton 2002; Rockstrom et al. 2009; Rohr et al. 2008; Steffen, Crutzen, and McNeill 2007; Thomas et al. 2004;…

Reorganization of a hospital catering system increases food intake in patients with inadequate intake

DEFF Research Database (Denmark)

Freil, M.; Nielsen, M. A.; Biltz, C.

2006-01-01

Background: Low food intake is a frequent problem in undernourished hospital patients. Objective: To study whether a reorganization of a hospital catering system enabling patients to choose their evening meal individually, in combination with an increase in the energy density of the food, increases......: Reorganization of a hospital catering system can increase energy and protein intake and reduce waste substantially. Keywords: hospital food; nutritional risk; undernutrition...

The Effect of Size and Ecology on Extinction Susceptibility

Science.gov (United States)

Huynh, C.; Yuan, A.; Heim, N.; Payne, J.

2015-12-01

Although life on Earth first emerged as prokaryotic organisms, it eventually evolved into billions of different species. However, extinctions on Earth, especially the five mass extinctions, have decimated species. So what leads to a species survival or demise during a mass extinction? Are certain species more susceptible to extinctions based on their size and ecology? For this project, we focused on the data of marine animals. To examine the impact of size and ecology on a species's likelihood of survival, we compared the sizes and ecologies of the survivors and victims of the five mass extinctions. The ecology, or life mode, of a genus consists of the combination of tiering, motility, and feeding mechanism. Tiering refers to the animal's typical location in the water column and sediments, motility refers to its ability to move, and feeding mechanism describes the way the organism eats; together, they describe the animal's behavior. We analyzed the effect of ecology on survival using logistic regression, which compares life mode to the success or failure of a genus during each mass extinction interval. For organism size, we found the extinct organisms' mean size (both volume and length) and compared it with the average size of survivors on a graph. Our results show that while surviving genera of mass extinctions tended to be slightly larger than those that went extinct, there was no significant difference. Even though the Permian (Changhsingian) and Triassic (Rhaetian) extinctions had larger surviving species, likewise the difference was small. Ecology had a more obvious impact on the likelihood of survival; fast-moving, predatory pelagic organisms were the most likely to go extinct, while sedentary, infaunal suspension feeders had the greatest chances of survival. Overall, ecology played a greater role than size in determining the survival of a species. With this information, we can use ecology to predict which species would survive future extinctions.

Enhancing Divergent Search through Extinction Events

DEFF Research Database (Denmark)

Lehman, Joel; Miikkulainen, Risto

2015-01-01

for the capacity to evolve. This hypothesis is tested through experiments in two evolutionary robotics domains. The results show that combining extinction events with divergent search increases evolvability, while combining them with convergent search offers no similar benefit. The conclusion is that extinction...

Power scaling and experimentally fitted model for broad area quantum cascade lasers in continuous wave operation

Science.gov (United States)

Suttinger, Matthew; Go, Rowel; Figueiredo, Pedro; Todi, Ankesh; Shu, Hong; Leshin, Jason; Lyakh, Arkadiy

2018-01-01

Experimental and model results for 15-stage broad area quantum cascade lasers (QCLs) are presented. Continuous wave (CW) power scaling from 1.62 to 2.34 W has been experimentally demonstrated for 3.15-mm long, high reflection-coated QCLs for an active region width increased from 10 to 20 μm. A semiempirical model for broad area devices operating in CW mode is presented. The model uses measured pulsed transparency current, injection efficiency, waveguide losses, and differential gain as input parameters. It also takes into account active region self-heating and sublinearity of pulsed power versus current laser characteristic. The model predicts that an 11% improvement in maximum CW power and increased wall-plug efficiency can be achieved from 3.15 mm×25 μm devices with 21 stages of the same design, but half doping in the active region. For a 16-stage design with a reduced stage thickness of 300 Å, pulsed rollover current density of 6 kA/cm2, and InGaAs waveguide layers, an optical power increase of 41% is projected. Finally, the model projects that power level can be increased to ˜4.5 W from 3.15 mm×31 μm devices with the baseline configuration with T0 increased from 140 K for the present design to 250 K.

Are Humans too Numerous to Become Extinct?

OpenAIRE

Cairns, John

2009-01-01

Some claim that humans are too numerous to become extinct. However, passenger pigeon, once the most numerous birds on the planet, are now extinct. For years, humankind has been damaging its habitat, discharging toxic chemicals into the environment, and having harmful effects on agricultural productivity due to climate change. Humankind s extinction depends on the continuation of various human activities including economic growth, addiction to fossil fuel, over consumption, overpopulation, oc...

Gourds and squashes (Cucurbita spp.) adapted to megafaunal extinction and ecological anachronism through domestication.

Science.gov (United States)

Kistler, Logan; Newsom, Lee A; Ryan, Timothy M; Clarke, Andrew C; Smith, Bruce D; Perry, George H

2015-12-08

The genus Cucurbita (squashes, pumpkins, gourds) contains numerous domesticated lineages with ancient New World origins. It was broadly distributed in the past but has declined to the point that several of the crops' progenitor species are scarce or unknown in the wild. We hypothesize that Holocene ecological shifts and megafaunal extinctions severely impacted wild Cucurbita, whereas their domestic counterparts adapted to changing conditions via symbiosis with human cultivators. First, we used high-throughput sequencing to analyze complete plastid genomes of 91 total Cucurbita samples, comprising ancient (n = 19), modern wild (n = 30), and modern domestic (n = 42) taxa. This analysis demonstrates independent domestication in eastern North America, evidence of a previously unknown pathway to domestication in northeastern Mexico, and broad archaeological distributions of taxa currently unknown in the wild. Further, sequence similarity between distant wild populations suggests recent fragmentation. Collectively, these results point to wild-type declines coinciding with widespread domestication. Second, we hypothesize that the disappearance of large herbivores struck a critical ecological blow against wild Cucurbita, and we take initial steps to consider this hypothesis through cross-mammal analyses of bitter taste receptor gene repertoires. Directly, megafauna consumed Cucurbita fruits and dispersed their seeds; wild Cucurbita were likely left without mutualistic dispersal partners in the Holocene because they are unpalatable to smaller surviving mammals with more bitter taste receptor genes. Indirectly, megafauna maintained mosaic-like landscapes ideal for Cucurbita, and vegetative changes following the megafaunal extinctions likely crowded out their disturbed-ground niche. Thus, anthropogenic landscapes provided favorable growth habitats and willing dispersal partners in the wake of ecological upheaval.

Reorganization of AECL and the future marketing program

International Nuclear Information System (INIS)

Donnelly, James

Atomic Energy of Canada Ltd. Engineering Co. has been reorganized to support the new emphasis on foreign sales of CANDU reactors. Much has been learned from reactor sales to Argentina, Korea, and Romania, but Canada needs to sell one 600 MWe reactor a year in order to avoid a decline in its nuclear industry. (LL)

A window of vulnerability: impaired fear extinction in adolescence.

Science.gov (United States)

Baker, Kathryn D; Den, Miriam L; Graham, Bronwyn M; Richardson, Rick

2014-09-01

There have been significant advances made towards understanding the processes mediating extinction of learned fear. However, despite being of clear theoretical and clinical significance, very few studies have examined fear extinction in adolescence, which is often described as a developmental window of vulnerability to psychological disorders. This paper reviews the relatively small body of research examining fear extinction in adolescence. A prominent finding of this work is that adolescents, both humans and rodents, exhibit a marked impairment in extinction relative to both younger (e.g., juvenile) and older (e.g., adult) groups. We then review some potential mechanisms that could produce the striking extinction deficit observed in adolescence. For example, one neurobiological candidate mechanism for impaired extinction in adolescence involves changes in the functional connectivity within the fear extinction circuit, particularly between prefrontal cortical regions and the amygdala. In addition, we review research on emotion regulation and attention processes that suggests that developmental changes in attention bias to threatening cues may be a cognitive mechanism that mediates age-related differences in extinction learning. We also examine how a differential reaction to chronic stress in adolescence impacts upon extinction retention during adolescence as well as in later life. Finally, we consider the findings of several studies illustrating promising approaches that overcome the typically-observed extinction impairments in adolescent rodents and that could be translated to human adolescents. Copyright © 2013 Elsevier Inc. All rights reserved.

Extinction of aversive classically conditioned human sexual response.

Science.gov (United States)

Brom, Mirte; Laan, Ellen; Everaerd, Walter; Spinhoven, Philip; Both, Stephanie

2015-04-01

Research has shown that acquired subjective likes and dislikes are quite resistant to extinction. Moreover, studies on female sexual response demonstrated that diminished genital arousal and positive affect toward erotic stimuli due to aversive classical conditioning did not extinguish during an extinction phase. Possible resistance to extinction of aversive conditioned sexual responses may have important clinical implications. However, resistance to extinction of aversive conditioned human sexual response has not been studied using extensive extinction trials. This article aims to study resistance to extinction of aversive conditioned sexual responses in sexually functional men and women. A differential conditioning experiment was conducted, with two erotic pictures as conditioned stimulus (CSs) and a painful stimulus as unconditioned stimuli (USs). Only one CS (the CS+) was followed by the US during the acquisition phase. Conditioned responses were assessed during the extinction phase. Penile circumference and vaginal pulse amplitude were assessed, and ratings of affective value and subjective sexual arousal were obtained. Also, a stimulus response compatibility task was included to assess automatic approach and avoidance tendencies. Men and women rated the CS+ more negative as compared with the CS-. During the first trials of the extinction phase, vaginal pulse amplitude was lower in response to the CS+ than in response to the CS-, and on the first extinction trial women rated the CS+ as less sexually arousing. Intriguingly, men did not demonstrate attenuated genital and subjective sexual response. Aversive conditioning, by means of painful stimuli, only affects sexual responses in women, whereas it does not in men. Although conditioned sexual likes and dislikes are relatively persistent, conditioned affect eventually does extinguish. © 2014 International Society for Sexual Medicine.

75 FR 61696 - Foreign-Trade Zone 51-Duluth, MN; Application for Reorganization Under Alternative Site Framework

Science.gov (United States)

2010-10-06

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [Docket 58-2010] Foreign-Trade Zone 51--Duluth... FTZ 51, requesting authority to reorganize the zone under the alternative site framework (ASF) adopted... or reorganizing a general-purpose zone, the application would have no impact on FTZ 51's authorized...

46 CFR 391.8 - Certain corporate reorganizations and changes in partnerships, and certain transfers on death...

Science.gov (United States)

2010-10-01

... 46 Shipping 8 2010-10-01 2010-10-01 false Certain corporate reorganizations and changes in..., DEPARTMENT OF TRANSPORTATION REGULATIONS UNDER PUBLIC LAW 91-469 FEDERAL INCOME TAX ASPECTS OF THE CAPITAL CONSTRUCTION FUND § 391.8 Certain corporate reorganizations and changes in partnerships, and certain transfers...

Selection, subdivision and extinction and recolonization.

Science.gov (United States)

Cherry, Joshua L

2004-02-01

In a subdivided population, the interaction between natural selection and stochastic change in allele frequency is affected by the occurrence of local extinction and subsequent recolonization. The relative importance of selection can be diminished by this additional source of stochastic change in allele frequency. Results are presented for subdivided populations with extinction and recolonization where there is more than one founding allele after extinction, where these may tend to come from the same source deme, where the number of founding alleles is variable or the founders make unequal contributions, and where there is dominance for fitness or local frequency dependence. The behavior of a selected allele in a subdivided population is in all these situations approximately the same as that of an allele with different selection parameters in an unstructured population with a different size. The magnitude of the quantity N(e)s(e), which determines fixation probability in the case of genic selection, is always decreased by extinction and recolonization, so that deleterious alleles are more likely to fix and advantageous alleles less likely to do so. The importance of dominance or frequency dependence is also altered by extinction and recolonization. Computer simulations confirm that the theoretical predictions of both fixation probabilities and mean times to fixation are good approximations.

Thermo-optically induced reorganizations in the main light harvesting antenna of plants. II

DEFF Research Database (Denmark)

Holm, Jens Kai; Varkonyi, Zsuzsanna; Kovacs, Laszlo

2005-01-01

We have investigated the circular dichroism spectral transients associated with the light-induced reversible reorganizations in chirally organized macrodomains of pea thylakoid membranes and loosely stacked lamellar aggregates of the main chlorophyll a/b light harvesting complexes (LHCII) isolated...... from the same membranes. These reorganizations have earlier been assigned to originate from a thermo-optic effect. According to the thermo-optic mechanism, fast local thermal transients due to dissipation of the excess excitation energy induce elementary structural changes in the close vicinity...

The Astronomical Pulse of Global Extinction Events

Directory of Open Access Journals (Sweden)

David F.V. Lewis

2006-01-01

Full Text Available The linkage between astronomical cycles and the periodicity of mass extinctions is reviewed and discussed. In particular, the apparent 26 million year cycle of global extinctions may be related to the motion of the solar system around the galaxy, especially perpendicular to the galactic plane. The potential relevance of Milankovitch cycles is also explored in the light of current evidence for the possible causes of extinction events over a geological timescale.

Instrument for long-path spectral extinction measurements in air: application to sizing of airborne particles

International Nuclear Information System (INIS)

Paganini, Enrico; Trespidi, Franco; Ferri, Fabio

2001-01-01

A novel instrument that is capable of taking spectral extinction measurements over long optical paths (approximately 1-100 m) in the UV, visible, and IR ranges is described. The instrument is fully automated, and the extinction spectrum is acquired in almost real time (approximately 5-10 s) with a resolution of ∼3 nm. Its sensitivity and accuracy were estimated by tests carried out in a clean room that showed that, for optical paths between 50 and 100 m, the extinction coefficient can be detected at levels of ∼10 -5 m -1 . Tests carried out on calibrated latex particles showed that, when it was combined with an appropriate inversion method, the technique could be profitably applied to characterize airborne particulate distributions. By carrying out measurements over optical paths of ∼100 m, the instrument is also capable of detecting extinction coefficients that are due to aerosol concentrations well below the limits imposed by the European Economic Community for atmospheric pollution (150 μg/m3). Scaled over optical paths of ∼10 m, the limit imposed for particle emissions from industrial plants (10 mg/m3) can also be detected sensitively

Global attractors and extinction dynamics of cyclically competing species.

Science.gov (United States)

Rulands, Steffen; Zielinski, Alejandro; Frey, Erwin

2013-05-01

Transitions to absorbing states are of fundamental importance in nonequilibrium physics as well as ecology. In ecology, absorbing states correspond to the extinction of species. We here study the spatial population dynamics of three cyclically interacting species. The interaction scheme comprises both direct competition between species as in the cyclic Lotka-Volterra model, and separated selection and reproduction processes as in the May-Leonard model. We show that the dynamic processes leading to the transient maintenance of biodiversity are closely linked to attractors of the nonlinear dynamics for the overall species' concentrations. The characteristics of these global attractors change qualitatively at certain threshold values of the mobility and depend on the relative strength of the different types of competition between species. They give information about the scaling of extinction times with the system size and thereby the stability of biodiversity. We define an effective free energy as the negative logarithm of the probability to find the system in a specific global state before reaching one of the absorbing states. The global attractors then correspond to minima of this effective energy landscape and determine the most probable values for the species' global concentrations. As in equilibrium thermodynamics, qualitative changes in the effective free energy landscape indicate and characterize the underlying nonequilibrium phase transitions. We provide the complete phase diagrams for the population dynamics and give a comprehensive analysis of the spatio-temporal dynamics and routes to extinction in the respective phases.

Infectious Disease, Endangerment, and Extinction

Science.gov (United States)

MacPhee, Ross D. E.; Greenwood, Alex D.

2013-01-01

Infectious disease, especially virulent infectious disease, is commonly regarded as a cause of fluctuation or decline in biological populations. However, it is not generally considered as a primary factor in causing the actual endangerment or extinction of species. We review here the known historical examples in which disease has, or has been assumed to have had, a major deleterious impact on animal species, including extinction, and highlight some recent cases in which disease is the chief suspect in causing the outright endangerment of particular species. We conclude that the role of disease in historical extinctions at the population or species level may have been underestimated. Recent methodological breakthroughs may lead to a better understanding of the past and present roles of infectious disease in influencing population fitness and other parameters. PMID:23401844

POST-RETRIEVAL EXTINCTION ATTENUATES ALCOHOL CUE REACTIVITY IN RATS

Science.gov (United States)

Cofresí, Roberto U.; Lewis, Suzanne M.; Chaudhri, Nadia; Lee, Hongjoo J.; Monfils, Marie-H.; Gonzales, Rueben A.

2017-01-01

BACKGROUND Conditioned responses to alcohol-associated cues can hinder recovery from alcohol use disorder (AUD). Cue exposure (extinction) therapy (CET) can reduce reactivity to alcohol cues, but its efficacy is limited by phenomena such as spontaneous recovery and reinstatement that can cause a return of conditioned responding after extinction. Using a preclinical model of alcohol cue reactivity in rats, we evaluated whether the efficacy of alcohol CET could be improved by conducting CET during the memory reconsolidation window after retrieval of a cue-alcohol association. METHODS Rats were provided with intermittent access to unsweetened alcohol. Rats were then trained to predict alcohol access based on a visual cue. Next, rats were treated with either standard extinction (n=14) or post-retrieval extinction (n=13). Rats were then tested for long-term memory of extinction and susceptibility to spontaneous recovery and reinstatement. RESULTS Despite equivalent extinction, rats treated with post-retrieval extinction exhibited reduced spontaneous recovery and reinstatement relative to rats treated with standard extinction. CONCLUSIONS Post-retrieval CET shows promise for persistently attenuating the risk to relapse posed by alcohol cues in individuals with AUD. PMID:28169439

Dust extinction in the first galaxies

Science.gov (United States)

Jaacks, Jason; Finkelstein, Steven L.; Bromm, Volker

2018-04-01

Using cosmological volume simulations and a custom built sub-grid model for Population III (Pop III) star formation, we examine the baseline dust extinction in the first galaxies due to Pop III metal enrichment in the first billion years of cosmic history. We find that although the most enriched, high-density lines of sight in primordial galaxies can experience a measurable amount of extinction from Pop III dust [E(B - V)max = 0.07, AV, max ≈ 0.28], the average extinction is very low with ≲ 10-3. We derive a power-law relationship between dark matter halo mass and extinction of E(B-V)∝ M_halo^{0.80}. Performing a Monte Carlo parameter study, we establish the baseline reddening of the ultraviolet spectra of dwarf galaxies at high redshift due to Pop III enrichment only. With this method, we find - 2.51 ± 0.07, which is both nearly halo mass and redshift independent.

Extinction vulnerability of coral reef fishes.

Science.gov (United States)

Graham, Nicholas A J; Chabanet, Pascale; Evans, Richard D; Jennings, Simon; Letourneur, Yves; Aaron Macneil, M; McClanahan, Tim R; Ohman, Marcus C; Polunin, Nicholas V C; Wilson, Shaun K

2011-04-01

With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate. © 2011 Blackwell Publishing Ltd/CNRS.

LINE DERIVED INFRARED EXTINCTION TOWARD THE GALACTIC CENTER

International Nuclear Information System (INIS)

Fritz, T. K.; Gillessen, S.; Dodds-Eden, K.; Lutz, D.; Genzel, R.; Raab, W.; Ott, T.; Pfuhl, O.; Eisenhauer, F.; Yusef-Zadeh, F.

2011-01-01

We derive the extinction curve toward the Galactic center (GC) from 1 to 19 μm. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction-free flux reference is the 2 cm continuum emission observed by the Very Large Array. Toward the inner 14'' x 20'', we find an extinction of A 2.166μm = 2.62 ± 0.11, with a power-law slope of α = -2.11 ± 0.06 shortward of 2.8 μm, consistent with the average near-infrared slope from the recent literature. At longer wavelengths, however, we find that the extinction is grayer than shortward of 2.8 μm. We find that it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only, and the addition of composite particles, including ices, is needed to explain the observations. Combining a distance-dependent extinction with our distance-independent extinction, we derive the distance to the GC to be R 0 = 7.94 ± 0.65 kpc. Toward Sgr A* (r H = 4.21 ± 0.10, A Ks = 2.42 ± 0.10, and A L' = 1.09 ± 0.13.

Malthusian Catastrophe: Species Extinction Caused By Oversized Population

OpenAIRE

Pan, Xubin

2017-01-01

There is one pseudo-extinction debt and four occurring conditions for real extinction debt. Since small and oversized populations have a high extinction risk, Pan threshold (upper limit) was calculated for Verhulst-Pear logistic growth model and logistic model with the Allee effect, an important parameter corresponding to Allee threshold (lower limit).

Experience with dynamic reinforcement rates decreases resistance to extinction.

Science.gov (United States)

Craig, Andrew R; Shahan, Timothy A

2016-03-01

The ability of organisms to detect reinforcer-rate changes in choice preparations is positively related to two factors: the magnitude of the change in rate and the frequency with which rates change. Gallistel (2012) suggested similar rate-detection processes are responsible for decreases in responding during operant extinction. Although effects of magnitude of change in reinforcer rate on resistance to extinction are well known (e.g., the partial-reinforcement-extinction effect), effects of frequency of changes in rate prior to extinction are unknown. Thus, the present experiments examined whether frequency of changes in baseline reinforcer rates impacts resistance to extinction. Pigeons pecked keys for variable-interval food under conditions where reinforcer rates were stable and where they changed within and between sessions. Overall reinforcer rates between conditions were controlled. In Experiment 1, resistance to extinction was lower following exposure to dynamic reinforcement schedules than to static schedules. Experiment 2 showed that resistance to presession feeding, a disruptor that should not involve change-detection processes, was unaffected by baseline-schedule dynamics. These findings are consistent with the suggestion that change detection contributes to extinction. We discuss implications of change-detection processes for extinction of simple and discriminated operant behavior and relate these processes to the behavioral-momentum based approach to understanding extinction. © 2016 Society for the Experimental Analysis of Behavior.

Candesartan ameliorates impaired fear extinction induced by innate immune activation.

Science.gov (United States)

Quiñones, María M; Maldonado, Lizette; Velazquez, Bethzaly; Porter, James T

2016-02-01

Patients with post-traumatic stress disorder (PTSD) tend to show signs of a relatively increased inflammatory state suggesting that activation of the immune system may contribute to the development of PTSD. In the present study, we tested whether activation of the innate immune system can disrupt acquisition or recall of auditory fear extinction using an animal model of PTSD. Male adolescent rats received auditory fear conditioning in context A. The next day, an intraperitoneal injection of lipopolysaccharide (LPS; 100 μg/kg) prior to auditory fear extinction in context B impaired acquisition and recall of extinction. LPS (100 μg/kg) given after extinction training did not impair extinction recall suggesting that LPS did not affect consolidation of extinction. In contrast to cued fear extinction, contextual fear extinction was not affected by prior injection of LPS (100 μg/kg). Although LPS also reduced locomotion, we could dissociate the effects of LPS on extinction and locomotion by using a lower dose of LPS (50 μg/kg) which impaired locomotion without affecting extinction. In addition, 15 h after an injection of 250 μg/kg LPS in adult rats, extinction learning and recall were impaired without affecting locomotion. A sub-chronic treatment with candesartan, an angiotensin II type 1 receptor blocker, prevented the LPS-induced impairment of extinction in adult rats. Our results demonstrate that activation of the innate immune system can disrupt auditory fear extinction in adolescent and adult animals. These findings also provide direction for clinical studies of novel treatments that modulate the innate immune system for stress-related disorders like PTSD. Copyright © 2015 Elsevier Inc. All rights reserved.

Extinction-Induced Variability in Human Behavior

Science.gov (United States)

Kinloch, Jennifer M.; Foster, T. Mary; McEwan, James S. A.

2009-01-01

Participants earned points by pressing a computer space bar (Experiment 1) or forming rectangles on the screen with the mouse (Experiment 2) under differential-reinforcement-of-low-rate schedules, followed by extinction. Variability in interresponse time (the contingent dimension) increased during extinction, as for Morgan and Lee (1996);…

Context and Behavioral Processes in Extinction

Science.gov (United States)

Bouton, Mark E.

2004-01-01

This article provides a selective review and integration of the behavioral literature on Pavlovian extinction. The first part reviews evidence that extinction does not destroy the original learning, but instead generates new learning that is especially context-dependent. The second part examines insights provided by research on several related…

Experimental Investigation of the Dietary Ecology of the Extinct Passenger Pigeon, Ectopistes migratorius

Directory of Open Access Journals (Sweden)

Ben J. Novak

2018-03-01

Full Text Available For tens of thousands of years, passenger pigeons (Ectopistes migratorius were a dominant member of eastern North American forest communities, with megaflocks comprising up to several billion individuals. The extinction of passenger pigeons in the early twentieth century undoubtedly influenced associated species and ecosystems as interactions stemming from the pigeons disappeared suddenly. Here, we strive to better understand what was probably one of the most significant of these interactions—that between passenger pigeons and seed bearing trees. Using the band-tailed pigeon (Patagioenas fasciata and the rock dove (Columba livia as physical and ecological proxies, we evaluated passenger pigeon dietary range and potential to disperse seeds. Our findings suggest that the passenger pigeon's dietary range, observed historically to be taxonomically broad, was constrained to certain seed sizes due to bill gape size. In addition, we conclude that the digestive process invariably destroyed consumed seeds but the potential for a nutrition/dispersal mutualism might still have existed via regurgitation and post-mortem release of crop contents. Our results highlight the range of ecological interactions that can be lost with species' extinction and the inherent challenge of understanding the consequences of those interactions.

Can CCM law properly represent all extinction curves?

International Nuclear Information System (INIS)

Geminale, Anna; Popowski, Piotr

2005-01-01

We present the analysis of a large sample of lines of sight with extinction curves covering wavelength range from near-infrared (NIR) to ultraviolet (UV). We derive total to selective extinction ratios based on the Cardelli, Clayton and Mathis (1989, CCM) law, which is typically used to fit the extinction data both for diffuse and dense interstellar medium. We conclude that the CCM law is able to fit most of the extinction curves in our sample. We divide the remaining lines of sight with peculiar extinction into two groups according to two main behaviors: a) the optical/IR or/and UV wavelength region cannot be reproduced by the CCM formula; b) the optical/NIR and UV extinction data are best fit by the CCM law with different values of R v . We present examples of such curves. The study of both types of peculiar cases can help us to learn about the physical processes that affect dust in the interstellar medium, e.g., formation of mantles on the surface of grains, evaporation, growing or shattering

Resistance to extinction, generalization decrement, and conditioned reinforcement.

Science.gov (United States)

Dulaney, Alana E; Bell, Matthew C

2008-06-01

This study investigated generalization decrement during an extinction resistance-to-change test for pigeon key pecking using a two-component multiple schedule with equal variable-interval 3-min schedules and different reinforcer amounts (one component presented 2-s access to reinforcement and the other 8s). After establishing baseline responding, subjects were assigned to one of the two extinction conditions: hopper stimuli (hopper and hopper light were activated but no food was available) or Control (inactive hopper and hopper light). Responding in the 8-s component was more resistant to extinction than responding in the 2-s component, the hopper stimuli group was more resistant to extinction compared to the Control group, and an interaction between amount of reinforcement, extinction condition, and session block was present. This finding supports generalization decrement as a factor that influences resistance to extinction. Hopper-time data (the amount of time subjects spent with their heads in the hopper) were compared to resistance-to-change data in an investigation of the role of conditioned reinforcement on resistance to change.

Psychological and neural mechanisms of experimental extinction: a selective review.

Science.gov (United States)

Delamater, Andrew R; Westbrook, R Frederick

2014-02-01

The present review examines key psychological concepts in the study of experimental extinction and implications these have for an understanding of the underlying neurobiology of extinction learning. We suggest that many of the signature characteristics of extinction learning (spontaneous recovery, renewal, reinstatement, rapid reacquisition) can be accommodated by the standard associative learning theory assumption that extinction results in partial erasure of the original learning together with new inhibitory learning. Moreover, we consider recent behavioral and neural evidence that supports the partial erasure view of extinction, but also note shortcomings in our understanding of extinction circuits as these relate to the negative prediction error concept. Recent work suggests that common prediction error and stimulus-specific prediction error terms both may be required to explain neural plasticity both in acquisition and extinction learning. In addition, we suggest that many issues in the content of extinction learning have not been fully addressed in current research, but that neurobiological approaches should be especially helpful in addressing such issues. These include questions about the nature of extinction learning (excitatory CS-No US, inhibitory CS-US learning, occasion setting processes), especially as this relates to studies of the micro-circuitry of extinction, as well as its representational content (sensory, motivational, response). An additional understudied problem in extinction research is the role played by attention processes and their underlying neural networks, although some research and theory converge on the idea that extinction is accompanied by attention decrements (i.e., habituation-like processes). Copyright © 2013 Elsevier Inc. All rights reserved.

Fear extinction requires infralimbic cortex projections to the basolateral amygdala.

Science.gov (United States)

Bloodgood, Daniel W; Sugam, Jonathan A; Holmes, Andrew; Kash, Thomas L

2018-03-06

Fear extinction involves the formation of a new memory trace that attenuates fear responses to a conditioned aversive memory, and extinction impairments are implicated in trauma- and stress-related disorders. Previous studies in rodents have found that the infralimbic prefrontal cortex (IL) and its glutamatergic projections to the basolateral amygdala (BLA) and basomedial amygdala (BMA) instruct the formation of fear extinction memories. However, it is unclear whether these pathways are exclusively involved in extinction, or whether other major targets of the IL, such as the nucleus accumbens (NAc) also play a role. To address this outstanding issue, the current study employed a combination of electrophysiological and chemogenetic approaches in mice to interrogate the role of IL-BLA and IL-NAc pathways in extinction. Specifically, we used patch-clamp electrophysiology coupled with retrograde tracing to examine changes in neuronal activity of the IL and prelimbic cortex (PL) projections to both the BLA and NAc following fear extinction. We found that extinction produced a significant increase in the intrinsic excitability of IL-BLA projection neurons, while extinction appeared to reverse fear-induced changes in IL-NAc projection neurons. To establish a causal counterpart to these observations, we then used a pathway-specific Designer Receptors Exclusively Activated by Designer Drugs (DREADD) strategy to selectively inhibit PFC-BLA projection neurons during extinction acquisition. Using this approach, we found that DREADD-mediated inhibition of PFC-BLA neurons during extinction acquisition impaired subsequent extinction retrieval. Taken together, our findings provide further evidence for a critical contribution of the IL-BLA neural circuit to fear extinction.

Effects of past and present livestock grazing on herpetofauna in a landscape-scale experiment.

Science.gov (United States)

Kay, Geoffrey M; Mortelliti, Alessio; Tulloch, Ayesha; Barton, Philip; Florance, Daniel; Cunningham, Saul A; Lindenmayer, David B

2017-04-01

Livestock grazing is the most widespread land use on Earth and can have negative effects on biodiversity. Yet, many of the mechanisms by which grazing leads to changes in biodiversity remain unresolved. One reason is that conventional grazing studies often target broad treatments rather than specific parameters of grazing (e.g., intensity, duration, and frequency) or fail to account for historical grazing effects. We conducted a landscape-scale replicated grazing experiment (15,000 km 2 , 97 sites) to examine the impact of past grazing management and current grazing regimes (intensity, duration, and frequency) on a community of ground-dwelling herpetofauna (39 species). We analyzed community variables (species richness and composition) for all species and built multiseason patch-occupancy models to predict local colonization and extinction for the 7 most abundant species. Past grazing practices did not influence community richness but did affect community composition and patch colonization and extinction for 4 of 7 species. Present grazing parameters did not influence community richness or composition, but 6 of the 7 target species were affected by at least one grazing parameter. Grazing frequency had the most consistent influence, positively affecting 3 of 7 species (increased colonization or decreased extinction). Past grazing practice affected community composition and population dynamics in some species in different ways, which suggests that conservation planners should examine the different grazing histories of an area. Species responded differently to specific current grazing practices; thus, incentive programs that apply a diversity of approaches rather than focusing on a change such as reduced grazing intensity should be considered. Based on our findings, we suggest that determining fine-scale grazing attributes is essential for advancing grazing as a conservation strategy. © 2016 Society for Conservation Biology.

Cortisol modifies extinction learning of recently acquired fear in men

Science.gov (United States)

Hermann, Andrea; Stark, Rudolf; Wolf, Oliver Tobias

2014-01-01

Exposure therapy builds on the mechanism of fear extinction leading to decreased fear responses. How the stress hormone cortisol affects brain regions involved in fear extinction in humans is unknown. For this reason, we tested 32 men randomly assigned to receive either 30 mg hydrocortisone or placebo 45 min before fear extinction. In fear acquisition, a picture of a geometrical figure was either partially paired (conditioned stimulus; CS+) or not paired (CS−) with an electrical stimulation (unconditioned stimulus; UCS). In fear extinction, each CS was presented again, but no UCS occurred. Cortisol increased conditioned skin conductance responses in early and late extinction. In early extinction, higher activation towards the CS− than to the CS+ was found in the amygdala, hippocampus and posterior parahippocampal gyrus. This pattern might be associated with the establishment of a new memory trace. In late extinction, the placebo compared with the cortisol group displayed enhanced CS+/CS− differentiation in the amygdala, medial frontal cortex and nucleus accumbens. A change from early deactivation to late activation of the extinction circuit as seen in the placebo group seems to be needed to enhance extinction and to reduce fear. Cortisol appears to interfere with this process thereby impairing extinction of recently acquired conditioned fear. PMID:23945999

The role of the medial prefrontal cortex in trace fear extinction

Science.gov (United States)

Kwapis, Janine L.; Jarome, Timothy J.

2015-01-01

The extinction of delay fear conditioning relies on a neural circuit that has received much attention and is relatively well defined. Whether this established circuit also supports the extinction of more complex associations, however, is unclear. Trace fear conditioning is a better model of complex relational learning, yet the circuit that supports extinction of this memory has received very little attention. Recent research has indicated that trace fear extinction requires a different neural circuit than delay extinction; trace extinction requires the participation of the retrosplenial cortex, but not the amygdala, as noted in a previous study. Here, we tested the roles of the prelimbic and infralimbic regions of the medial prefrontal cortex in trace and delay fear extinction by blocking NMDA receptors during extinction learning. We found that the prelimbic cortex is necessary for trace, but not for delay fear extinction, whereas the infralimbic cortex is involved in both types of extinction. These results are consistent with the idea that trace fear associations require plasticity in multiple cortical areas for successful extinction. Further, the infralimbic cortex appears to play a role in extinction regardless of whether the animal was initially trained in trace or delay conditioning. Together, our results provide new information about how the neural circuits supporting trace and delay fear extinction differ. PMID:25512576

Accelerated modern human?induced species losses: Entering the sixth mass extinction

OpenAIRE

Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; Garc?a, Andr?s; Pringle, Robert M.; Palmer, Todd M.

2015-01-01

The oft-repeated claim that Earth?s biota is entering a sixth ?mass extinction? depends on clearly demonstrating that current extinction rates are far above the ?background? rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we...

The atmospheric extinction of light

International Nuclear Information System (INIS)

Hughes, Stephen W; Powell, Sean; Carroll, Joshua; Cowley, Michael

2016-01-01

An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm −1 respectively and 0.032, 0.037 and 0.092 cm −1 for the Picotech Dr. DAQ ADC. (paper)

Forelimb training drives transient map reorganization in ipsilateral motor cortex.

Science.gov (United States)

Pruitt, David T; Schmid, Ariel N; Danaphongse, Tanya T; Flanagan, Kate E; Morrison, Robert A; Kilgard, Michael P; Rennaker, Robert L; Hays, Seth A

2016-10-15

Skilled motor training results in reorganization of contralateral motor cortex movement representations. The ipsilateral motor cortex is believed to play a role in skilled motor control, but little is known about how training influences reorganization of ipsilateral motor representations of the trained limb. To determine whether training results in reorganization of ipsilateral motor cortex maps, rats were trained to perform the isometric pull task, an automated motor task that requires skilled forelimb use. After either 3 or 6 months of training, intracortical microstimulation (ICMS) mapping was performed to document motor representations of the trained forelimb in the hemisphere ipsilateral to that limb. Motor training for 3 months resulted in a robust expansion of right forelimb representation in the right motor cortex, demonstrating that skilled motor training drives map plasticity ipsilateral to the trained limb. After 6 months of training, the right forelimb representation in the right motor cortex was significantly smaller than the representation observed in rats trained for 3 months and similar to untrained controls, consistent with a normalization of motor cortex maps. Forelimb map area was not correlated with performance on the trained task, suggesting that task performance is maintained despite normalization of cortical maps. This study provides new insights into how the ipsilateral cortex changes in response to skilled learning and may inform rehabilitative strategies to enhance cortical plasticity to support recovery after brain injury. Copyright © 2016 Elsevier B.V. All rights reserved.

Permian-Triassic thermal anomaly of the active margin of South America as a result of plate kinematics reorganization

Science.gov (United States)

Riel, Nicolas; Jaillard, Etienne; Guillot, Stéphane; Martelat, Jean-Emmanuel; Braun, Jean

2013-04-01

From Permian to Triassic times, tectonic plate reorganization provoked Pangaea breakup, counterclockwise rotation of Gondwana, closing of the Paleo-Tethys Ocean and opening of the Neo-Tethys oceanic realm. Meanwhile, the switch from arc volcanism to widespread S-type magmatism along the western South American active margin around 275-265 Ma is symptomatic of the onset of a large-scale Permian-Triassic thermal anomaly (PTTA)affecting the whole margin. Here we report metamorphic and U-Pb geochronological results from the El Oro metamorphic complex in the forearc zone of southwestern Ecuador, which recorded the last step, at 230-225 Ma, of the PTTA. The change in the drift direction of Gondwana from north to east at ca. 270 Ma was related to plate reorganization and provoked the verticalization of the subducted Panthalassa slab. As the slab verticalized, strong heat advection produced a high heat flow beneath the active margin inducing the development of a huge thermal anomaly responsible for the PTTA, which lasted 30 Ma. This voluminous magmatic activity culminated at the Permian-Triassic boundary, and may have contributed to the degradation of life conditions on the Earth surface.

Acute stress impairs the retrieval of extinction memory in humans

Science.gov (United States)

Raio, Candace M.; Brignoni-Perez, Edith; Goldman, Rachel; Phelps, Elizabeth A.

2014-01-01

Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays an important role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent research in rodents found that exposure to stress led to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress responses, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, one day later participants in the stress group (n = 27) demonstrated significantly less

Can Parallelingualism Save Norwegian from Extinction?

Science.gov (United States)

Linn, Andrew R.

2010-01-01

Language extinction is one of the most pressing issues in linguistics today, and the literature is full of discussion about how to combat it. Statements that Norwegian is amongst the languages that are already extinct are merely examples of a widespread tendency in the literature towards erroneous information about Norwegian. Nonetheless, there is…

Endangered Species and Natural Resource Exploitation: Extinction vs. Coexistence

OpenAIRE

Tsur, Yacov; Zemel, Amos

1994-01-01

The threat on the survival of animal species due to intensive use of natural resources is incorporated within resource management models, paying special attention to uncertainty regarding the conditions that lead to extinction. The manner in which the potential benefits forgone due to the species extinction (denoted extinction penalty) induce more conservative exploitation policies is studied in detail. When the extinction penalty is ignored, the optimal policy is to drive the resource stock ...

Motor Cortex Reorganization in Patients with Glioma Assessed by Repeated Navigated Transcranial Magnetic Stimulation-A Longitudinal Study.

Science.gov (United States)

Barz, Anne; Noack, Anika; Baumgarten, Peter; Seifert, Volker; Forster, Marie-Therese

2018-04-01

Evidence for cerebral reorganization after resection of low-grade glioma has mainly been obtained by serial intraoperative cerebral mapping. Noninvasively collected data on cortical plasticity in tumor patients over a surgery-free period are still scarce. The present study therefore aimed at evaluating motor cortex reorganization by navigated transcranial magnetic stimulation (nTMS) in patients after perirolandic glioma surgery. nTMS was performed preoperatively and postoperatively in 20 patients, separated by 26.1 ± 24.8 months. Further nTMS mapping was conducted in 14 patients, resulting in a total follow-up period of 46.3 ± 25.4 months. Centers of gravity (CoGs) were calculated for every muscle representation area, and Euclidian distances between CoGs over time were defined. Results were compared with data from 12 healthy individuals, who underwent motor cortex mapping by nTMS in 2 sessions. Preoperatively and postoperatively pooled CoGs from the area of the dominant abductor pollicis brevis muscle and of the nondominant leg area differed significantly compared with healthy individuals (P < 0.05). Most remarkably, during the ensuing follow-up period, a reorganization of all representation areas was observed in 3 patients, and a significant shift of hand representation areas was identified in further 3 patients. Complete functional recovery of postoperative motor deficits was exclusively associated with cortical reorganization. Despite the low potential of remodeling within the somatosensory region, long-term reorganization of cortical motor function can be observed. nTMS is best suited for a noninvasive evaluation of this reorganization. Copyright © 2018 Elsevier Inc. All rights reserved.

Drilling reorganizes

Science.gov (United States)

Richman, Barbara T.

As the first in a proposed series of steps that would move scientific ocean drilling from its own niche within the National Science Foundation's (NSF) Directorate for Astronomical, Atmospheric, Earth, and Ocean Sciences (AAEO) into the agency's Division of Ocean Sciences, Grant Gross, division director, has been appointed acting director of the Office of Scientific Ocean Drilling (OSOD). Gross will retain the directorship of the division, which also is part of AAEO. Allen M. Shinn, Jr., OSOD director for nearly 2 years, has been reassigned effective July 10 to a position in NSF's Office of Planning and Resource Management.The move aims to tie drilling operations more closely to the science with which it is associated, Gross said. This first step is an organizational response to the current leaning toward using a commercial drilling vessel as the drilling platform, he said. Before the market for such commercial drill ships opened (Eos, February 22, 1983, p . 73), other ship options for scientific ocean drilling included refurbishing the aging Glomar Challenger or renovating, at great expense, the Glomar Explorer. A possible next step in the reorganization is to make OSOD the third section within the Ocean Sciences Division. Currently, the division is divided into the Oceanographic Facilities and Support Section and the Ocean Sciences Research Section.

Drying induced upright sliding and reorganization of carbon nanotube arrays

International Nuclear Information System (INIS)

Li Qingwen; De Paula, Raymond; Zhang Xiefei; Zheng Lianxi; Arendt, Paul N; Mueller, Fred M; Zhu, Y T; Tu Yi

2006-01-01

Driven by capillary force, wet carbon nanotube (CNT) arrays have been found to reorganize into cellular structures upon drying. During the reorganization process, individual CNTs are firmly attached to the substrate and have to lie down on the substrate at cell bottoms, forming closed cells. Here we demonstrate that by modifying catalyst structures, the adhesion of CNTs to the substrate can be weakened. Upon drying such CNT arrays, CNTs may slide away from their original sites on the surface and self-assemble into cellular patterns with bottoms open. It is also found that the sliding distance of CNTs increases with array height, and drying millimetre tall arrays leads to the sliding of CNTs over a few hundred micrometres and the eventual self-assembly into discrete islands. By introducing regular vacancies in CNT arrays, CNTs may be manipulated into different patterns

Nature and Causes of the Immediate Extinction Deficit: A Brief Review

OpenAIRE

Maren, Stephen

2013-01-01

Recent data in both rodents and humans suggests that the timing of extinction trials after conditioning influences the magnitude and duration of extinction. For example, administering extinction trials soon after Pavlovian fear conditioning in rats, mice, and humans results in minimal fear suppression--the so-called immediate extinction deficit. Here I review recent work examining the behavioral and neural substrates of the immediate extinction deficit. I suggest that extinction is most effec...

Effects of sleep on memory for conditioned fear and fear extinction

Science.gov (United States)

Pace-Schott, Edward F.; Germain, Anne; Milad, Mohammed R.

2015-01-01

Learning and memory for extinction of conditioned fear is a basic mammalian mechanism for regulating negative emotion. Sleep promotes both the consolidation of memory and the regulation of emotion. Sleep can influence consolidation and modification of memories associated with both fear and its extinction. After brief overviews of the behavior and neural circuitry associated with fear conditioning, extinction learning and extinction memory in the rodent and human, interactions of sleep with these processes will be examined. Animal and human studies suggest that sleep can serve to consolidate both fear and extinction memory. In humans, sleep also promotes generalization of extinction memory. Time-of-day effects on extinction learning and generalization are also seen. REM may be a sleep stage of particular importance for the consolidation of both fear and extinction memory as evidenced by selective REM deprivation experiments. REM sleep is accompanied by selective activation of the same limbic structures implicated in the learning and memory of fear and extinction. Preliminary evidence also suggests extinction learning can take place during slow wave sleep. Study of low-level processes such as conditioning, extinction and habituation may allow sleep effects on emotional memory to be identified and inform study of sleep’s effects on more complex, emotionally salient declarative memories. Anxiety disorders are marked by impairments of both sleep and extinction memory. Improving sleep quality may ameliorate anxiety disorders by strengthening naturally acquired extinction. Strategically timed sleep may be used to enhance treatment of anxiety by strengthening therapeutic extinction learned via exposure therapy. PMID:25894546

Effects of sleep on memory for conditioned fear and fear extinction.

Science.gov (United States)

Pace-Schott, Edward F; Germain, Anne; Milad, Mohammed R

2015-07-01

Learning and memory for extinction of conditioned fear is a basic mammalian mechanism for regulating negative emotion. Sleep promotes both the consolidation of memory and the regulation of emotion. Sleep can influence consolidation and modification of memories associated with both fear and its extinction. After brief overviews of the behavior and neural circuitry associated with fear conditioning, extinction learning, and extinction memory in the rodent and human, interactions of sleep with these processes will be examined. Animal and human studies suggest that sleep can serve to consolidate both fear and extinction memory. In humans, sleep also promotes generalization of extinction memory. Time-of-day effects on extinction learning and generalization are also seen. Rapid eye movement (REM) may be a sleep stage of particular importance for the consolidation of both fear and extinction memory as evidenced by selective REM deprivation experiments. REM sleep is accompanied by selective activation of the same limbic structures implicated in the learning and memory of fear and extinction. Preliminary evidence also suggests extinction learning can take place during slow wave sleep. Study of low-level processes such as conditioning, extinction, and habituation may allow sleep effects on emotional memory to be identified and inform study of sleep's effects on more complex, emotionally salient declarative memories. Anxiety disorders are marked by impairments of both sleep and extinction memory. Improving sleep quality may ameliorate anxiety disorders by strengthening naturally acquired extinction. Strategically timed sleep may be used to enhance treatment of anxiety by strengthening therapeutic extinction learned via exposure therapy. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Nature and causes of the immediate extinction deficit: a brief review.

Science.gov (United States)

Maren, Stephen

2014-09-01

Recent data in both rodents and humans suggests that the timing of extinction trials after conditioning influences the magnitude and duration of extinction. For example, administering extinction trials soon after Pavlovian fear conditioning in rats, mice, and humans results in minimal fear suppression - the so-called immediate extinction deficit. Here I review recent work examining the behavioral and neural substrates of the immediate extinction deficit. I suggest that extinction is most effective at some delay after conditioning, because brain systems involved in encoding and retrieving extinction memories function sub-optimally under stress. Copyright © 2013 Elsevier Inc. All rights reserved.

Clinical neurorehabilitation - implications of the Reorganization of Elementary Functions (REF) model

DEFF Research Database (Denmark)

Rytter, Hana Malá; Mogensen, Jesper

The REF (Reorganization of Elementary Functions) model suggests mechanisms of posttraumatic reorganization, and resolves the contradiction between localization and functional recovery. In the process of developing this model, we have reconceptualised the term ‘function’ and introduced a concept...... across situations and cognitive domains. Since novel ASs are created and selected according to situation dependent feedback mechanisms, dissimilar external conditions may call for different ASs. Consequently, therapeutically established ASs may not be adequate in the settings of daily life. Additionally......, upon the loss of a particular brain structure, the structure and networks mediating recovery will not be identical in case of different cognitive and situational demands. Therapeutically, an important implication is that rehabilitative training should include as naturalistic settings as possible....

ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

Energy Technology Data Exchange (ETDEWEB)

Peek, J. E. G.; Schiminovich, David, E-mail: jegpeek@gmail.com [Department of Astronomy, Columbia University, New York, NY (United States)

2013-07-01

In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is {approx}10% and {approx}35% higher than expected, with significant variation across the sky. We find that no single R{sub V} parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

International Nuclear Information System (INIS)

Peek, J. E. G.; Schiminovich, David

2013-01-01

In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is ∼10% and ∼35% higher than expected, with significant variation across the sky. We find that no single R V parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

Reorganization of the power distribution sector in India

International Nuclear Information System (INIS)

Dossani, Rafiq

2004-01-01

This paper presents the central issues for electricity-sector reform in India, as they grew out of the reform process that began in 1991, and within the context of the sector's organization, regulatory structure, and other institutional characteristics. The paper argues that India's current reform policies will not be sufficient to achieve reliable, efficient power because distribution reform has not been done. Undertaking distribution reform is a difficult path to tread because of the absence of global consensus on best practices and conflicting forces, both economic and political. The paper analyzes alternative institutional structures for reform in the distribution sector. The findings include that the objectives of coverage and efficiency may conflict, that economically efficient reorganization may be politically unachievable and that the small, municipally owned firm may be the best compromise. Since many Indian states are economically and politically diverse from each other, and include both large served and unserved areas, there is scope to vary the organizational structure depending on the state's situation. This paper provides a means to do so. The agenda for policymakers is to identify the situation in their respective states and choose a reorganization path that is the best compromise

Has the Earth's sixth mass extinction already arrived?

Science.gov (United States)

Barnosky, Anthony D; Matzke, Nicholas; Tomiya, Susumu; Wogan, Guinevere O U; Swartz, Brian; Quental, Tiago B; Marshall, Charles; McGuire, Jenny L; Lindsey, Emily L; Maguire, Kaitlin C; Mersey, Ben; Ferrer, Elizabeth A

2011-03-03

Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.

d-Cycloserine reduces context specificity of sexual extinction learning.

Science.gov (United States)

Brom, Mirte; Laan, Ellen; Everaerd, Walter; Spinhoven, Philip; Trimbos, Baptist; Both, Stephanie

2015-11-01

d-Cycloserine (DCS) enhances extinction processes in animals. Although classical conditioning is hypothesized to play a pivotal role in the aetiology of appetitive motivation problems, no research has been conducted on the effect of DCS on the reduction of context specificity of extinction in human appetitive learning, while facilitation hereof is relevant in the context of treatment of problematic reward-seeking behaviors. Female participants were presented with two conditioned stimuli (CSs) that either predicted (CS+) or did not predict (CS-) a potential sexual reward (unconditioned stimulus (US); genital vibrostimulation). Conditioning took place in context A and extinction in context B. Subjects received DCS (125mg) or placebo directly after the experiment on day 1 in a randomized, double-blind, between-subject fashion (Placebo n=31; DCS n=31). Subsequent testing for CS-evoked conditioned responses (CRs) in both the conditioning (A) and the extinction context (B) took place 24h later on day 2. Drug effects on consolidation were then assessed by comparing the recall of sexual extinction memories between the DCS and the placebo groups. Post learning administration of DCS facilitates sexual extinction memory consolidation and affects extinction's fundamental context specificity, evidenced by reduced conditioned genital and subjective sexual responses, relative to placebo, for presentations of the reward predicting cue 24h later outside the extinction context. DCS makes appetitive extinction memories context-independent and prevents the return of conditioned response. NMDA receptor glycine site agonists may be potential pharmacotherapies for the prevention of relapse of appetitive motivation disorders with a learned component. Copyright © 2015 Elsevier Inc. All rights reserved.

Extinction of Learned Fear Induces Hippocampal Place Cell Remapping

Science.gov (United States)

Wang, Melissa E.; Yuan, Robin K.; Keinath, Alexander T.; Ramos Álvarez, Manuel M.

2015-01-01

The extinction of learned fear is a hippocampus-dependent process thought to embody new learning rather than erasure of the original fear memory, although it is unknown how these competing contextual memories are represented in the hippocampus. We previously demonstrated that contextual fear conditioning results in hippocampal place cell remapping and long-term stabilization of novel representations. Here we report that extinction learning also induces place cell remapping in C57BL/6 mice. Specifically, we observed cells that preferentially remapped during different stages of learning. While some cells remapped in both fear conditioning and extinction, others responded predominantly during extinction, which may serve to modify previous representations as well as encode new safe associations. Additionally, we found cells that remapped primarily during fear conditioning, which could facilitate reacquisition of the original fear association. Moreover, we also observed cells that were stable throughout learning, which may serve to encode the static aspects of the environment. The short-term remapping observed during extinction was not found in animals that did not undergo fear conditioning, or when extinction was conducted outside of the conditioning context. Finally, conditioning and extinction produced an increase in spike phase locking to the theta and gamma frequencies. However, the degree of remapping seen during conditioning and extinction only correlated with gamma synchronization. Our results suggest that the extinction learning is a complex process that involves both modification of pre-existing memories and formation of new ones, and these traces coexist within the same hippocampal representation. PMID:26085635

Adrenalectomy eliminates the extinction spike in autoshaping with rats.

Science.gov (United States)

Thomas, B L; Papini, M R

2001-03-01

Experiment 1, using rats, investigated the effect of adrenalectomy (ADX) on the invigoration of lever-contact performance that occurs in the autoshaping situation after a shift from acquisition to extinction (called the extinction spike). Groups of rats with ADX or sham operations were trained under spaced and massed conditions [average intertrial intervals (ITI) of either 15 or 90 s] for 10 sessions and then shifted to extinction. ADX did not affect acquisition training but it eliminated the extinction spike. Plasma corticosterone levels during acquisition were shown in Experiment 2 to be similar in rats trained under spaced or massed conditions. Adrenal participation in the emotional arousal induced by conditions of surprising nonreward (e.g., extinction) is discussed.

Reconsidering the extinction of ichthyosaurs

OpenAIRE

Fischer, Valentin

2010-01-01

Despite their extreme adaptation to life in open sea, ichthyosaurs were one of the first major groups of post-Triassic marine reptiles to disappear, at the end of Cenomanian, whereas plesiosaurs, mosasaurs and numerous families of marine crocodiles and sea turtles disappeared during the Cretaceous/Paleocene Extinction Event. It has been proposed that unique biological factors drove ichthyosaurs to extinction, namely a break in the food chain at the level of belemnites or a progressive ecologi...

Quantitative analysis of forest fire extinction efficiency

Directory of Open Access Journals (Sweden)

Miguel E. Castillo-Soto

2015-08-01

Full Text Available Aim of study: Evaluate the economic extinction efficiency of forest fires, based on the study of fire combat undertaken by aerial and terrestrial means. Area of study, materials and methods: Approximately 112,000 hectares in Chile. Records of 5,876 forest fires that occurred between 1998 and 2009 were analyzed. The area further provides a validation sector for results, by incorporating databases for the years 2010 and 2012. The criteria used for measuring extinction efficiency were economic value of forestry resources, Contraction Factor analysis and definition of the extinction costs function. Main results: It is possible to establish a relationship between burnt area, extinction costs and economic losses. The method proposed may be used and adapted to other fire situations, requiring unit costs for aerial and terrestrial operations, economic value of the property to be protected and speed attributes of fire spread in free advance. Research highlights: The determination of extinction efficiency in containment works of forest fires and potential projection of losses, different types of plant fuel and local conditions favoring the spread of fire broaden the admissible ranges of a, φ and Ce considerably.

Late Pleistocene and Holocene mammal extinctions on continental Africa

Science.gov (United States)

Faith, J. Tyler

2014-01-01

Understanding the cause of late Quaternary mammal extinctions is the subject of intense debate spanning the fields of archeology and paleontology. In the global context, the losses on continental Africa have received little attention and are poorly understood. This study aims to inspire new discussion of African extinctions through a review of the extinct species and the chronology and possible causes of those extinctions. There are at least 24 large mammal (> 5 kg) species known to have disappeared from continental Africa during the late Pleistocene or Holocene, indicating a much greater taxonomic breadth than previously recognized. Among the better sampled taxa, these losses are restricted to the terminal Pleistocene and early Holocene, between 13,000 and 6000 yrs ago. The African extinctions preferentially affected species that are grazers or prefer grasslands. Where good terrestrial paleoenvironmental records are present, extinctions are associated with changes in the availability, productivity, or structure of grassland habitats, suggesting that environmental changes played a decisive role in the losses. In the broader evolutionary context, these extinctions represent recent examples of selective taxonomic winnowing characterized by the loss of grassland specialists and the establishment of large mammal communities composed of more ecologically flexible taxa over the last million years. There is little reason to believe that humans played an important role in African extinctions.

Defining the period of moa extinction

International Nuclear Information System (INIS)

Anderson, A.

2000-01-01

Few aspects of New Zealand's prehistory have engaged scientific and public attention so consistently as two interlinked questions of moa extinction; when did moas become extinct and why? Answers offered over the last 160 years have run the gamut from chronological antiquity by evolutionary senescence, to within the 19th century Maori and European disturbance. (author)

Genetic disruptions of Drosophila Pavlovian learning leave extinction learning intact.

Science.gov (United States)

Qin, H; Dubnau, J

2010-03-01

Individuals who experience traumatic events may develop persistent posttraumatic stress disorder. Patients with this disorder are commonly treated with exposure therapy, which has had limited long-term success. In experimental neurobiology, fear extinction is a model for exposure therapy. In this behavioral paradigm, animals are repeatedly exposed in a safe environment to the fearful stimulus, which leads to greatly reduced fear. Studying animal models of extinction already has lead to better therapeutic strategies and development of new candidate drugs. Lack of a powerful genetic model of extinction, however, has limited progress in identifying underlying molecular and genetic factors. In this study, we established a robust behavioral paradigm to study the short-term effect (acquisition) of extinction in Drosophila melanogaster. We focused on the extinction of olfactory aversive 1-day memory with a task that has been the main workhorse for genetics of memory in flies. Using this paradigm, we show that extinction can inhibit each of two genetically distinct forms of consolidated memory. We then used a series of single-gene mutants with known impact on associative learning to examine the effects on extinction. We find that extinction is intact in each of these mutants, suggesting that extinction learning relies on different molecular mechanisms than does Pavlovian learning.

Broad Scale Monitoring in the US Forest Service: Institutional Challenges and Collaborative Opportunites for Improving Planning and Decision-Making in an Era of Climate Change

Science.gov (United States)

Wurtzebach, Z.

2016-12-01

In 2012, the United States Forest Service promulgated new rules to guide Forest planning efforts in accordance with the National Forest Management Act (NFMA). One important component of the 2012 rule is a requirement for Regionally coordinated cross-boundary "broad scale" monitoring strategies that are designed to inform and facilitate Forest-level adaptive management and planning. This presentation will examine institutional challenges and opportunites for developing effective broad scale monitoring strategies identified in 90 interviews with USFS staff and partner organizations, and collaborative workshops held in Colorado, Wyoming, Arizona, and New Mexico. Internal barriers to development include funding and human resource constraints, organizational culture, problematic incentives and accountability structures, data management issues, and administrative barriers to collaboration. However, we also identify several opportunities for leveraging interagency collaboration, facilitating multi-level coordination, generating efficiencies in data collection and analysis, and improving strategies for reporting and communication to Forest level decision-makers and relevant stakeholders.

Flourishing ocean drives the end-Permian marine mass extinction.

Science.gov (United States)

Schobben, Martin; Stebbins, Alan; Ghaderi, Abbas; Strauss, Harald; Korn, Dieter; Korte, Christoph

2015-08-18

The end-Permian mass extinction, the most severe biotic crisis in the Phanerozoic, was accompanied by climate change and expansion of oceanic anoxic zones. The partitioning of sulfur among different exogenic reservoirs by biological and physical processes was of importance for this biodiversity crisis, but the exact role of bioessential sulfur in the mass extinction is still unclear. Here we show that globally increased production of organic matter affected the seawater sulfate sulfur and oxygen isotope signature that has been recorded in carbonate rock spanning the Permian-Triassic boundary. A bifurcating temporal trend is observed for the strata spanning the marine mass extinction with carbonate-associated sulfate sulfur and oxygen isotope excursions toward decreased and increased values, respectively. By coupling these results to a box model, we show that increased marine productivity and successive enhanced microbial sulfate reduction is the most likely scenario to explain these temporal trends. The new data demonstrate that worldwide expansion of euxinic and anoxic zones are symptoms of increased biological carbon recycling in the marine realm initiated by global warming. The spatial distribution of sulfidic water column conditions in shallow seafloor environments is dictated by the severity and geographic patterns of nutrient fluxes and serves as an adequate model to explain the scale of the marine biodiversity crisis. Our results provide evidence that the major biodiversity crises in Earth's history do not necessarily implicate an ocean stripped of (most) life but rather the demise of certain eukaryotic organisms, leading to a decline in species richness.

Neural signals of vicarious extinction learning.

Science.gov (United States)

Golkar, Armita; Haaker, Jan; Selbing, Ida; Olsson, Andreas

2016-10-01

Social transmission of both threat and safety is ubiquitous, but little is known about the neural circuitry underlying vicarious safety learning. This is surprising given that these processes are critical to flexibly adapt to a changeable environment. To address how the expression of previously learned fears can be modified by the transmission of social information, two conditioned stimuli (CS + s) were paired with shock and the third was not. During extinction, we held constant the amount of direct, non-reinforced, exposure to the CSs (i.e. direct extinction), and critically varied whether another individual-acting as a demonstrator-experienced safety (CS + vic safety) or aversive reinforcement (CS + vic reinf). During extinction, ventromedial prefrontal cortex (vmPFC) responses to the CS + vic reinf increased but decreased to the CS + vic safety This pattern of vmPFC activity was reversed during a subsequent fear reinstatement test, suggesting a temporal shift in the involvement of the vmPFC. Moreover, only the CS + vic reinf association recovered. Our data suggest that vicarious extinction prevents the return of conditioned fear responses, and that this efficacy is reflected by diminished vmPFC involvement during extinction learning. The present findings may have important implications for understanding how social information influences the persistence of fear memories in individuals suffering from emotional disorders. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Prefrontal single-unit firing associated with deficient extinction in mice

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Fitzgerald, Paul J; Whittle, Nigel; Flynn, Shaun M; Graybeal, Carolyn; Pinard, Courtney; Gunduz-Cinar, Ozge; Kravitz, Alexxai; Singewald, Nicolas; Holmes, Andrew

2014-01-01

The neural circuitry mediating fear extinction has been increasingly well studied and delineated. The rodent infralimbic subregion (IL) of the ventromedial prefrontal cortex (vmPFC) has been found to promote extinction, whereas the prelimbic cortex (PL) demonstrates an opposing, pro-fear, function. Studies employing in vivo electrophysiological recordings have observed that while increased IL single-unit firing and bursting predicts robust extinction retrieval, increased PL firing can correlate with sustained fear and poor extinction. These relationships between single-unit firing and extinction do not hold under all experimental conditions, however. In the current study, we further investigated the relationship between vmPFC and PL single-unit firing and extinction using inbred mouse models of intact (C57BL/6J, B6) and deficient (129S1/SvImJ, S1) extinction strains. Simultaneous single-unit recordings were made in the PL and vmPFC (encompassing IL) as B6 and S1 mice performed extinction training and retrieval. Impaired extinction retrieval in S1 mice was associated with elevated PL single-unit firing, as compared to firing in extinguishing B6 mice, consistent with the hypothesized pro-fear contribution of PL. Analysis of local field potentials also revealed significantly higher gamma power in the PL of Sthan B6 mice during extinction training and retrieval. In the vmPFC, impaired extinction in S1 mice was also associated with exaggerated single-unit firing, relative to B6 mice. This is in apparent contradiction to evidence that IL activity promotes extinction, but could reflect a (failed) compensatory effort by the vmPFC to mitigate fear-promoting activity in other regions, such as the PL or amygdala. In support of this hypothesis, augmenting IL activity via direct infusion of the GABAA receptor antagonist picrotoxin rescued impaired extinction retrieval in S1 mice. Chronic fluoxetine treatment produced modest reductions in fear during extinction retrieval and

Role of the hippocampus in contextual modulation of fear extinction

Institute of Scientific and Technical Information of China (English)

Lingzhi Kong; Xihong Wu; Liang Li

2008-01-01

Fear extinction is an important form of emotional learning, and affects neural plasticity. Cue fear extinction is a classical form of inhibitory learning that can be used as an exposure-based treatment for phobia, because the long-term extinction memory produced during cue fear extinction can limit the over-expression of fear. The expression of this inhibitory memory partly depends on the context in which the extinction learning occurs. Studies such as transient inhibition, electrophysiology and brain imaging have proved that the hippocampus - an important structure in the limbic system - facilitates memory retrieval by contextual cues.Mediation of the hippocampus-medial prefrontal lobe circuit may be the neurobiological basis of this process.This article has reviewed the role of the hippocampus in the learning and retrieval of fear extinction.Contextual modulation of fear extinction may rely on a neural network consisting of the hippocampus, the medial prefrontal cortex and the amygdala.

A global synthesis of plant extinction rates in urban areas.

Science.gov (United States)

Hahs, Amy K; McDonnell, Mark J; McCarthy, Michael A; Vesk, Peter A; Corlett, Richard T; Norton, Briony A; Clemants, Steven E; Duncan, Richard P; Thompson, Ken; Schwartz, Mark W; Williams, Nicholas S G

2009-11-01

Plant extinctions from urban areas are a growing threat to biodiversity worldwide. To minimize this threat, it is critical to understand what factors are influencing plant extinction rates. We compiled plant extinction rate data for 22 cities around the world. Two-thirds of the variation in plant extinction rates was explained by a combination of the city's historical development and the current proportion of native vegetation, with the former explaining the greatest variability. As a single variable, the amount of native vegetation remaining also influenced extinction rates, particularly in cities > 200 years old. Our study demonstrates that the legacies of landscape transformations by agrarian and urban development last for hundreds of years, and modern cities potentially carry a large extinction debt. This finding highlights the importance of preserving native vegetation in urban areas and the need for mitigation to minimize potential plant extinctions in the future.

12 CFR 5.32 - Expedited procedures for certain reorganizations.

Science.gov (United States)

2010-01-01

... section 3 of the National Bank Consolidation and Merger Act, 12 U.S.C. 215a(a)(2); and (v) Describes any changes to the bank's business plan resulting from the reorganization. (3) Financial and managerial... impact of the proposed affiliation on the financial and managerial resources and future prospects of the...

Connectivity of a large embayment and coastal fishery: spawning aggregations in one bay source local and broad-scale fishery replenishment.

Science.gov (United States)

Hamer, P A; Acevedo, S; Jenkins, G P; Newman, A

2011-04-01

Ichthyoplankton sampling and otolith chemistry were used to determine the importance of transient spawning aggregations of snapper Chrysophrys auratus (Sparidae) in a large embayment, Port Phillip Bay (PPB), Australia, as a source of local and broad-scale fishery replenishment. Ichthyoplankton sampling across five spawning seasons within PPB, across the narrow entrance to the bay and in adjacent coastal waters, indicated that although spawning may occur in coastal waters, the spawning aggregations within the bay were the primary source of larval recruitment to the bay. Otolith chemical signatures previously characterized for 0+ year C. auratus of two cohorts (2000 and 2001) were used as the baseline signatures to quantify the contribution that fish derived from reproduction in PPB make to fishery replenishment. Sampling of these cohorts over a 5 year period at various widely dispersed fishery regions, combined with maximum likelihood analyses of the chemistry of the 0+ year otolith portions of these older fish, indicated that C. auratus of 1 to 3+ years of age displayed both local residency and broad-scale emigration from PPB to populate coastal waters and an adjacent bay (Western Port). While the PPB fishery was consistently dominated (>70%) by locally derived fish irrespective of cohort or age, the contribution of fish that had originated from PPB to distant populations increased with age. At 4 to 5+ years of age, when C. auratus mature and fully recruit to the fishery, populations of both cohorts across the entire central and western Victorian fishery, including two major embayments and c. 800 km of coastal waters, were dominated (>70%) by fish that had originated from the spawning aggregations and nursery habitat within PPB. Dependence of this broadly dispersed fishery on replenishment from heavily targeted spawning aggregations within one embayment has significant implications for management and monitoring programmes. © 2011 The Authors. Journal of Fish

Bilateral experimental neck pain reorganize axioscapular muscle coordination and pain sensitivity.

Science.gov (United States)

Christensen, S W; Hirata, R P; Graven-Nielsen, T

2017-04-01

Neck pain is a large clinical problem where reorganized trunk and axioscapular muscle activities have been hypothesised contributing to pain persistence and pain hypersensitivity. This study investigated the effects of bilateral experimental neck pain on trunk and axioscapular muscle function and pain sensitivity. In 25 healthy volunteers, bilateral experimental neck pain was induced in the splenius capitis muscles by hypertonic saline injections. Isotonic saline was used as control. In sitting, subjects performed slow, fast and slow-resisted unilateral arm movements before, during and after injections. Electromyography (EMG) was recorded from eight shoulder and trunk muscles bilaterally. Pressure pain thresholds (PPTs) were assessed bilaterally at the neck, head and arm. Data were normalized to the before-measures. Compared with control and post measurements, experimental neck pain caused (1) decreased EMG activity of the ipsilateral upper trapezius muscles during all but slow-resisted down movements (p neck pain reorganized axioscapular and trunk muscle activity together with local hyperalgesia and widespread hypoalgesia indicating that acute neck pain immediately affects trunk and axioscapular function which may affect both assessment and treatment. Bilateral clinical neck pain alters axioscapular muscle coordination but only effects of unilateral experimental neck pain has been investigated. Bilateral experimental neck pain causes task-dependent reorganized axioscapular and trunk muscle activity in addition to widespread decrease in pressure pain sensitivity. © 2016 European Pain Federation - EFIC®.

Post-Learning Sleep Transiently Boosts Context Specific Operant Extinction Memory

Directory of Open Access Journals (Sweden)

Marion Inostroza

2017-04-01

Full Text Available Operant extinction is learning to supress a previously rewarded behavior. It is known to be strongly associated with the specific context in which it was acquired, which limits the therapeutic use of operant extinction in behavioral treatments, e.g., of addiction. We examined whether sleep influences contextual memory of operant extinction over time, using two different recall tests (Recent and Remote. Rats were trained in an operant conditioning task (lever press in context A, then underwent extinction training in context B, followed by a 3-h retention period that contained either spontaneous morning sleep, morning sleep deprivation, or spontaneous evening wakefulness. A recall test was performed either immediately after the 3-h experimental retention period (Recent recall or after 48 h (Remote, in the extinction context B and in a novel context C. The two main findings were: (i at the Recent recall test, sleep in comparison with sleep deprivation and spontaneous wakefulness enhanced extinction memory but, only in the extinction context B; (ii at the Remote recall, extinction performance after sleep was enhanced in both contexts B and C to an extent comparable to levels at Recent recall in context B. Interestingly, extinction performance at Remote recall was also improved in the sleep deprivation groups in both contexts, with no difference to performance in the sleep group. Our results suggest that 3 h of post-learning sleep transiently facilitate the context specificity of operant extinction at a Recent recall. However, the improvement and contextual generalization of operant extinction memory observed in the long-term, i.e., after 48 h, does not require immediate post-learning sleep.

Extinction and dust properties in a clumpy medium

OpenAIRE

Scicluna, P.; Siebenmorgen, R.

2015-01-01

(abridged) The dust content of the universe is primarily explored via its interaction with stellar photons, producing interstellar extinction. However, owing to the physical extension of the observing beam, observations may detect scattered photons, resulting in a change in the observed (or effective) extinction, depending on the spatial distribution of the dust and the resolution of the instrument. We investigate the influence of clumpy dust distributions on effective extinction toward embed...

Dynamics of Population on the Verge of Extinction

OpenAIRE

Oborny, B.; Meszena, G.; Szabo, G.

2005-01-01

Theoretical considerations suggest that extinction in dispersal-limited populations is necessarily a threshold-like process that is analogous to a critical phase transition in physics. We use this analogy to find robust, common features in the dynamics of extinctions, and suggest early warning signals which may indicate that a population is endangered. As the critical threshold of extinction is approached, the population spontaneously fragments into discrete subpopulations and, consequently, ...

Deficient fear extinction memory in posttraumatic stress disorder.

Science.gov (United States)

Wicking, Manon; Steiger, Frauke; Nees, Frauke; Diener, Slawomira J; Grimm, Oliver; Ruttorf, Michaela; Schad, Lothar R; Winkelmann, Tobias; Wirtz, Gustav; Flor, Herta

2016-12-01

Posttraumatic stress disorder (PTSD) might be maintained by deficient extinction memory. We used a cued fear conditioning design with extinction and a post-extinction phase to provoke the return of fear and examined the role of the interplay of amygdala, hippocampus and prefrontal regions. We compared 18 PTSD patients with two healthy control groups: 18 trauma-exposed subjects without PTSD (nonPTSD) and 18 healthy controls (HC) without trauma experience. They underwent a three-day ABC-conditioning procedure in a functional magnetic resonance imaging scanner. Two geometric shapes that served as conditioned stimuli (CS) were presented in the context of virtual reality scenes. Electric painful stimuli were delivered after one of the two shapes (CS+) during acquisition (in context A), while the other (CS-) was never paired with pain. Extinction was performed in context B and extinction memory was tested in a novel context C. The PTSD patients showed significantly higher differential skin conductance responses than the non-PTSD and HC and higher differential amygdala and hippocampus activity than the HC in context C. In addition, elevated arousal to the CS+ during extinction and to the CS- throughout the experiment was present in the PTSD patients but self-reported differential valence or contingency were not different. During extinction recall, differential amygdala activity correlated positively with the intensity of numbing and ventromedial prefrontal cortex activity correlated positively with behavioral avoidance. PTSD patients show heightened return of fear in neural and peripheral measures. In addition, self-reported arousal was high to both danger (CS+) and safety (CS-) cues. These results suggest that a deficient maintenance of extinction and a failure to identify safety signals might contribute to PTSD symptoms, whereas non-PTSD subjects seem to show normal responses. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of D-cycloserine on the extinction of appetitive operant learning.

Science.gov (United States)

Vurbic, Drina; Gold, Benjamin; Bouton, Mark E

2011-08-01

Four experiments with rat subjects examined whether D-cycloserine (DCS), a partial NMDA agonist, facilitates the extinction of operant lever-pressing reinforced by food. Previous research has demonstrated that DCS facilitates extinction learning with methods that involve Pavlovian extinction. In the current experiments, operant conditioning occurred in Context A, extinction in Context B, and then testing occurred in both the extinction and conditioning contexts. Experiments 1A and 1B tested the effects of three doses of DCS (5, 15, and 30 mg/kg) on the extinction of lever pressing trained as a free operant. Experiment 2 examined their effects when extinction of the free operant was conducted in the presence of nonresponse-contingent deliveries of the reinforcer (that theoretically reduced the role of generalization decrement in suppressing responding). Experiment 3 examined their effects on extinction of a discriminated operant, that is, one that had been reinforced in the presence of a discriminative stimulus, but not in its absence. A strong ABA renewal effect was observed in all four experiments during testing. However, despite the use of DCS doses and a drug administration procedure that facilitates the extinction of Pavlovian learning, there was no evidence in any experiment that DCS facilitated operant extinction learning assessed in either the extinction or the conditioning context. DCS may primarily facilitate learning processes that underlie Pavlovian, rather than purely operant, extinction. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

Directory of Open Access Journals (Sweden)

R. Thalman

2010-12-01

Full Text Available The combination of Cavity Enhanced Absorption Spectroscopy (CEAS with broad-band light sources (e.g. Light-Emitting Diodes, LEDs lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I₀. We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420–490 nm to measure nitrogen dioxide (NO₂, glyoxal (CHOCHO, methyl glyoxal (CH₃COCHO, iodine oxide (IO, water vapour (H₂O and oxygen dimers (O₄. We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O₄ or H₂O (at 477 nm and 443 nm and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3–7 × 10⁻⁷cm⁻¹. Excellent agreement is found from both the O₄ and H₂O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH₃COCHO, NO₂, H₂O and aerosol extinction. Our prototype

The IDC-thesaurus and its reorganization

International Nuclear Information System (INIS)

Senf, W.

1979-04-01

Final report on the IDC-Thesaurus and its reorganization. The Thesaurus set up for documentation of chemistry and its borderline areas is built up of concept sets. These concept sets unite all synonyms and are linked by concept relations reflecting the hierarchical structure of the Thesaurus. Analysis of the polyhierarchy of the Thesaurus. Composite concepts are subdivided into their broader terms of the abstraction system. These concepts as well as words with different spelling are transferred from the retrieval Thesaurus to a Thesaurus dictionary from which a file is set up for correcting the complete documentation file. (orig.) 891 WB 892 MB [de

Recovery effects after extinction in the Morris swimming pool navigation task.

Science.gov (United States)

Prados, José; Manteiga, Raúl D; Sansa, Joan

2003-08-01

In three experiments in which rats were used as subjects, we developed an extinction procedure using a Morris pool. The animals were trained to find a hidden platform located at a fixed position and were then given extinction trials in which the platform was removed from the pool. When training and extinction were carried out in the same context and time was allowed to elapse between extinction and test, spontaneous recovery of learning was observed. On the other hand, those rats that received extinction in a context different from the one used for training failed to show spontaneous recovery of learning when tested in the extinction context after an interval of 96 h. However, they did show renewal of spatial learning when tested in the training context. These results show that extinction in the spatial domain behaves like extinction in standard conditioning preparations.

Field Validation of Habitat Suitability Models for Vulnerable Marine Ecosystems in the South Pacific Ocean: Implications for the use of Broad-scale Models in Fisheries Management

Science.gov (United States)

Anderson, O. F.; Guinotte, J. M.; Clark, M. R.; Rowden, A. A.; Mormede, S.; Davies, A. J.; Bowden, D.

2016-02-01

Spatial management of vulnerable marine ecosystems requires accurate knowledge of their distribution. Predictive habitat suitability modelling, using species presence data and a suite of environmental predictor variables, has emerged as a useful tool for inferring distributions outside of known areas. However, validation of model predictions is typically performed with non-independent data. In this study, we describe the results of habitat suitability models constructed for four deep-sea reef-forming coral species across a large region of the South Pacific Ocean using MaxEnt and Boosted Regression Tree modelling approaches. In order to validate model predictions we conducted a photographic survey on a set of seamounts in an un-sampled area east of New Zealand. The likelihood of habitat suitable for reef forming corals on these seamounts was predicted to be variable, but very high in some regions, particularly where levels of aragonite saturation, dissolved oxygen, and particulate organic carbon were optimal. However, the observed frequency of coral occurrence in analyses of survey photographic data was much lower than expected, and patterns of observed versus predicted coral distribution were not highly correlated. The poor performance of these broad-scale models is attributed to lack of recorded species absences to inform the models, low precision of global bathymetry models, and lack of data on the geomorphology and substrate of the seamounts at scales appropriate to the modelled taxa. This demonstrates the need to use caution when interpreting and applying broad-scale, presence-only model results for fisheries management and conservation planning in data poor areas of the deep sea. Future improvements in the predictive performance of broad-scale models will rely on the continued advancement in modelling of environmental predictor variables, refinements in modelling approaches to deal with missing or biased inputs, and incorporation of true absence data.

Aging accelerates memory extinction and impairs memory restoration in Drosophila.

Science.gov (United States)

Chen, Nannan; Guo, Aike; Li, Yan

2015-05-15

Age-related memory impairment (AMI) is a phenomenon observed from invertebrates to human. Memory extinction is proposed to be an active inhibitory modification of memory, however, whether extinction is affected in aging animals remains to be elucidated. Employing a modified paradigm for studying memory extinction in fruit flies, we found that only the stable, but not the labile memory component was suppressed by extinction, thus effectively resulting in higher memory loss in aging flies. Strikingly, young flies were able to fully restore the stable memory component 3 h post extinction, while aging flies failed to do so. In conclusion, our findings reveal that both accelerated extinction and impaired restoration contribute to memory impairment in aging animals. Copyright © 2015 Elsevier Inc. All rights reserved.

Size distribution of interstellar particles. III. Peculiar extinctions and normal infrared extinction

International Nuclear Information System (INIS)

Mathis, J.S.; Wallenhorst, S.G.

1981-01-01

The effect of changing the upper and lower size limits of a distribution of bare graphite and silicate particles with n(a)αa/sup -q/ is investigated. Mathis, Rumpl, and Nordsieck showed that the normal extinction is matched very well by having the small-size cutoff, a/sub -/, roughly-equal0.005 or 0.01 μm, and the large size a/sub +/, about 0.25 μm, and q = 3.5 for both substances. We consider the progressively peculiar extinctions exhibited by the well-observed stars, sigma Sco, rho Oph, and theta 1 Ori C, with values of R/sub v/[equivalentA/sub v//E(B--V)] of 3.4, 4.4, and 5.5 compared to the normal 3.1. Two (sigma Sco, rho Oph) are in a neutral dense cloud; theta 1 Ori C is in the Orion Nebula. We find that sigma Sco has a normal graphite distribution but has had its small silicate particles removed, so that a/sub -/(sil)roughly-equal0.04 μm if q = 3.5, or q(sil) = 2.6 if the size limits are fixed. However, the upper size limit on silicates remains normal. In rho Oph, the graphite is still normal, but both a/sub -/(sil) and a/sub +/(sil) are increased, to about 0.04 μm and 0.4 or 0.5 μm, respectively, if q = 3.5, or q(sil)roughly-equal1.3 if the size limits are fixed. In theta 1 Ori, the small limit on graphite has increased to about 0.04 μm, or q(gra)roughly-equal3, while the silicates are about like those in rho Oph. The calculated lambda2175 bump is broader than the observed, but normal foreground extinction probably contributes appreciably to the observed bump. The absolute amount of extinction per H atom for rho Oph is not explained. The column density of H is so large that systematic effects might be present. Very large graphite particles (a>3 μm) are required to ''hide'' the graphite without overly affecting the visual extinction, but a normal (small) graphite size distribution is required by the lambda2175 bump. We feel that it is unlikely that such a bimodal distribution exists

The ultraviolet interstellar extinction curve in the Pleiades

Science.gov (United States)

Witt, A. N.; Bohlin, R. C.; Stecher, T. P.

1981-01-01

The wavelength dependence of ultraviolet extinction in the Pleiades dust clouds has been determined from IUE observations of HD 23512, the brightest heavily reddened member of the Pleiades cluster. There is evidence for an anomalously weak absorption bump at 2200 A, followed by an extinction rise in the far ultraviolet with an essentially normal slope. A relatively weak absorption band at 2200 A and a weak diffuse absorption band at 4430 A seem to be common characteristics of dust present in dense clouds. Evidence is presented which suggests that the extinction characteristics found for HD 23512 are typical for a class of extinction curves observed in several cases in the Galaxy and in the LMC.

Interstellar extinction in the Small Magellanic Cloud

International Nuclear Information System (INIS)

Nandy, K.; McLachlan, A.; Thompson, G.I.; Morgan, D.H.; Willis, A.J.; Wilson, R.; Gondhalekar, P.M.; Houziaux, L.

1982-01-01

IUE observations of three considerably reddened stars located near the core of the Small Magellanic Cloud and of two comparison stars which are also SMC members are presented. This region contains a considerable amount of dust. The UV spectrum of one of the reddened stars (BBB 338) shows the lambda 2200 feature characteristic of the Galactic extinction curve. This absorption feature is not obvious in the UV spectra of the other two reddened stars. Due to lack of a suitable comparison star it has not been possible to measure the UV extinction of BBB 338. The extinction curves derived for the other two reddened SMC members differ from the mean Galactic law in that they exhibit very weak or absent lambda 2200 and much higher values of far-UV extinction. These differences are greater than have been found for stars in the Large Magellanic Cloud, confirming earlier observations by others. (author)

Extinction and renewal of cue-elicited reward-seeking.

Science.gov (United States)

Bezzina, Louise; Lee, Jessica C; Lovibond, Peter F; Colagiuri, Ben

2016-12-01

Reward cues can contribute to overconsumption of food and drugs and can relapse. The failure of exposure therapies to reduce overconsumption and relapse is generally attributed to the context-specificity of extinction. However, no previous study has examined whether cue-elicited reward-seeking (as opposed to cue-reactivity) is sensitive to context renewal. We tested this possibility in 160 healthy volunteers using a Pavlovian-instrumental transfer (PIT) design involving voluntary responding for a high value natural reward (chocolate). One reward cue underwent Pavlovian extinction in the same (Group AAA) or different context (Group ABA) to all other phases. This cue was compared with a second non-extinguished reward cue and an unpaired control cue. There was a significant overall PIT effect with both reward cues eliciting reward-seeking on test relative to the unpaired cue. Pavlovian extinction substantially reduced this effect, with the extinguished reward cue eliciting less reward-seeking than the non-extinguished reward cue. Most interestingly, extinction of cue-elicited reward-seeking was sensitive to renewal, with extinction less effective for reducing PIT when conducted in a different context. These findings have important implications for extinction-based interventions for reducing maladaptive reward-seeking in practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

Slower Reacquisition after Partial Extinction in Human Contingency Learning

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Morís, Joaquín; Barberia, Itxaso; Vadillo, Miguel A.; Andrades, Ainhoa; López, Francisco J.

2017-01-01

Extinction is a very relevant learning phenomenon from a theoretical and applied point of view. One of its most relevant features is that relapse phenomena often take place once the extinction training has been completed. Accordingly, as extinction-based therapies constitute the most widespread empirically validated treatment of anxiety disorders,…

Extinction of radiant energy by large atmospheric crystals with different shapes

International Nuclear Information System (INIS)

Shefer, Olga

2016-01-01

The calculated results of extinction characteristics of visible and infrared radiation for large semi-transparent crystals are obtained by hybrid technique, which is a combination of the geometric optics method and the physical optics method. Energy and polarization characteristics of the radiation extinction in terms of the elements of the extinction matrix for individual large crystals and ensemble of crystals are discussed. Influences of particle shapes, aspect ratios, parameters of size distribution, complex refractive index, orientation of crystals, wavelength, and the polarization state of an incident radiation on the extinction are illustrated. It is shown that the most expressive and stable features of energy and polarization characteristics of the extinction are observed in the midinfrared region, despite the fact that the ice particles significantly absorb the radiant energy of this spectrum. It is demonstrated that the polarized extinction characteristics can reach several tens of percent at IR wavelengths. For the large crystals, the conditions of occurrence of the spectral behavior of the extinction coefficient in the visible, near-IR, and mid-IR wavelength ranges are determined. - Highlights: • Method of physical optics is used at coherent sum of diffracted and refracted fields. • The extinction characteristics in terms of elements of extinction matrix are obtained. • Influence of shapes and sizes of large particles on the extinction is evaluated. • Conditions of occurrence of extinction features are determined.

Associative learning versus fear habituation as predictors of long-term extinction retention.

Science.gov (United States)

Brown, Lily A; LeBeau, Richard T; Chat, Ka Yi; Craske, Michelle G

2017-06-01

Violation of unconditioned stimulus (US) expectancy during extinction training may enhance associative learning and result in improved long-term extinction retention compared to within-session habituation. This experiment examines variation in US expectancy (i.e., expectancy violation) as a predictor of long-term extinction retention. It also examines within-session habituation of fear-potentiated startle (electromyography, EMG) and fear of conditioned stimuli (CS) throughout extinction training as predictors of extinction retention. Participants (n = 63) underwent fear conditioning, extinction and retention and provided continuous ratings of US expectancy and EMG, as well as CS fear ratings before and after each phase. Variation in US expectancy throughout extinction and habituation of EMG and fear was entered into a regression as predictors of retention and reinstatement of levels of expectancy and fear. Greater variation in US expectancy throughout extinction training was significantly predictive of enhanced extinction performance measured at retention test, although not after reinstatement test. Slope of EMG and CS fear during extinction did not predict retention of extinction. Within-session habituation of EMG and self-reported fear is not sufficient for long-term retention of extinction learning, and models emphasizing expectation violation may result in enhanced outcomes.

Compound stimulus extinction reduces spontaneous recovery in humans

OpenAIRE

Coelho, Cesar A.O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.

2015-01-01

Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design (“deepened extinction”) shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately paired with an electric shock. The target CS (CSA) was extinguished alone followed by compound presentations of the extinguished CSA and nonextinguished CSB. Reco...

Confounding environmental colour and distribution shape leads to underestimation of population extinction risk.

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Fowler, Mike S; Ruokolainen, Lasse

2013-01-01

The colour of environmental variability influences the size of population fluctuations when filtered through density dependent dynamics, driving extinction risk through dynamical resonance. Slow fluctuations (low frequencies) dominate in red environments, rapid fluctuations (high frequencies) in blue environments and white environments are purely random (no frequencies dominate). Two methods are commonly employed to generate the coloured spatial and/or temporal stochastic (environmental) series used in combination with population (dynamical feedback) models: autoregressive [AR(1)] and sinusoidal (1/f) models. We show that changing environmental colour from white to red with 1/f models, and from white to red or blue with AR(1) models, generates coloured environmental series that are not normally distributed at finite time-scales, potentially confounding comparison with normally distributed white noise models. Increasing variability of sample Skewness and Kurtosis and decreasing mean Kurtosis of these series alter the frequency distribution shape of the realised values of the coloured stochastic processes. These changes in distribution shape alter patterns in the probability of single and series of extreme conditions. We show that the reduced extinction risk for undercompensating (slow growing) populations in red environments previously predicted with traditional 1/f methods is an artefact of changes in the distribution shapes of the environmental series. This is demonstrated by comparison with coloured series controlled to be normally distributed using spectral mimicry. Changes in the distribution shape that arise using traditional methods lead to underestimation of extinction risk in normally distributed, red 1/f environments. AR(1) methods also underestimate extinction risks in traditionally generated red environments. This work synthesises previous results and provides further insight into the processes driving extinction risk in model populations. We must let

Medial prefrontal cortex activation facilitates re-extinction of fear in rats

OpenAIRE

Chang, Chun-hui; Maren, Stephen

2011-01-01

It has been suggested that reduced infralimbic (IL) cortical activity contributes to impairments of fear extinction. We therefore explored whether pharmacological activation of the IL would facilitate extinction under conditions it normally fails (i.e., immediate extinction). Rats received auditory fear conditioning 1 h before extinction training. Immediately prior to extinction, rats received microinfusions into the IL of the GABAA receptor antagonist, picrotoxin, or the NMDA receptor partia...

Fibroblast Growth Factor-2 Alters the Nature of Extinction

Science.gov (United States)

Graham, Bronwyn M.; Richardson, Rick

2011-01-01

These experiments examined the effects of the NMDA-receptor (NMDAr) antagonist MK801 on reacquisition and re-extinction of a conditioned fear that had been previously extinguished before injection of fibroblast growth factor-2 (FGF2) or vehicle. Recent findings have shown that relearning and re-extinction, unlike initial learning and extinction,…

Accelerated modern human-induced species losses: Entering the sixth mass extinction.

Science.gov (United States)

Ceballos, Gerardo; Ehrlich, Paul R; Barnosky, Anthony D; García, Andrés; Pringle, Robert M; Palmer, Todd M

2015-06-01

The oft-repeated claim that Earth's biota is entering a sixth "mass extinction" depends on clearly demonstrating that current extinction rates are far above the "background" rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.

Relationship of extinction to perceptual thresholds for single stimuli.

Science.gov (United States)

Meador, K J; Ray, P G; Day, L J; Loring, D W

2001-04-24

To demonstrate the effects of target stimulus intensity on extinction to double simultaneous stimuli. Attentional deficits contribute to extinction in patients with brain lesions, but extinction (i.e., masking) can also be produced in healthy subjects. The relationship of extinction to perceptual thresholds for single stimuli remains uncertain. Brief electrical pulses were applied simultaneously to the left and right index fingers of 16 healthy volunteers (8 young and 8 elderly adults) and 4 patients with right brain stroke (RBS). The stimulus to be perceived (i.e., target stimulus) was given at the lowest perceptual threshold to perceive any single stimulus (i.e., Minimal) and at the threshold to perceive 100% of single stimuli. The mask stimulus (i.e., stimulus given to block the target) was applied to the contralateral hand at intensities just below discomfort. Extinction was less for target stimuli at 100% than Minimal threshold for healthy subjects. Extinction of left targets was greater in patients with RBS than elderly control subjects. Left targets were extinguished less than right in healthy subjects. In contrast, the majority of left targets were extinguished in patients with RBS even when right mask intensity was reduced below right 100% threshold for single stimuli. RBS patients had less extinction for right targets despite having greater left mask - threshold difference than control subjects. In patients with RBS, right "targets" at 100% threshold extinguished left "masks" (20%) almost as frequently as left masks extinguished right targets (32%). Subtle changes in target intensity affect extinction in healthy adults. Asymmetries in mask and target intensities (relative to single-stimulus perceptual thresholds) affect extinction in RBS patients less for left targets but more for right targets as compared with control subjects.

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation

Science.gov (United States)

Metcalf, Jessica L.; Turney, Chris; Barnett, Ross; Martin, Fabiana; Bray, Sarah C.; Vilstrup, Julia T.; Orlando, Ludovic; Salas-Gismondi, Rodolfo; Loponte, Daniel; Medina, Matías; De Nigris, Mariana; Civalero, Teresa; Fernández, Pablo Marcelo; Gasco, Alejandra; Duran, Victor; Seymour, Kevin L.; Otaola, Clara; Gil, Adolfo; Paunero, Rafael; Prevosti, Francisco J.; Bradshaw, Corey J. A.; Wheeler, Jane C.; Borrero, Luis; Austin, Jeremy J.; Cooper, Alan

2016-01-01

The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.6 ka) but during contrasting temperature trends across each continent. Unfortunately, limited data sets in South America have so far precluded detailed comparison. We analyze genetic and radiocarbon data from 89 and 71 Patagonian megafaunal bones, respectively, more than doubling the high-quality Pleistocene megafaunal radiocarbon data sets from the region. We identify a narrow megafaunal extinction phase 12,280 ± 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts. PMID:27386563

Breed locally, disperse globally: Fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist

Science.gov (United States)

Jennifer C. Pierson; Fred W. Allendorf; Pierre Drapeau; Michael K. Schwartz

2013-01-01

An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic...

Large impact of reorganization energy on photovoltaic conversion due to interfacial charge-transfer transitions.

Science.gov (United States)

Fujisawa, Jun-ichi

2015-05-14

Interfacial charge-transfer (ICT) transitions are expected to be a novel charge-separation mechanism for efficient photovoltaic conversion featuring one-step charge separation without energy loss. Photovoltaic conversion due to ICT transitions has been investigated using several TiO2-organic hybrid materials that show organic-to-inorganic ICT transitions in the visible region. In applications of ICT transitions to photovoltaic conversion, there is a significant problem that rapid carrier recombination is caused by organic-inorganic electronic coupling that is necessary for the ICT transitions. In order to solve this problem, in this work, I have theoretically studied light-to-current conversions due to the ICT transitions on the basis of the Marcus theory with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. An apparent correlation between the reported incident photon-to-current conversion efficiencies (IPCE) and calculated reorganization energies was clearly found, in which the IPCE increases with decreasing the reorganization energy consistent with the Marcus theory in the inverted region. This activation-energy dependence was systematically explained by the equation formulated by the Marcus theory based on a simple excited-state kinetic scheme. This result indicates that the reduction of the reorganization energy can suppress the carrier recombination and enhance the IPCE. The reorganization energy is predominantly governed by the structural change in the chemical-adsorption moiety between the ground and ICT excited states. This work provides crucial knowledge for efficient photovoltaic conversion due to ICT transitions.

Opposite effects of fear conditioning and extinction on dendritic spine remodelling.

Science.gov (United States)

Lai, Cora Sau Wan; Franke, Thomas F; Gan, Wen-Biao

2012-02-19

It is generally believed that fear extinction is a form of new learning that inhibits rather than erases previously acquired fear memories. Although this view has gained much support from behavioural and electrophysiological studies, the hypothesis that extinction causes the partial erasure of fear memories remains viable. Using transcranial two-photon microscopy, we investigated how neural circuits are modified by fear learning and extinction by examining the formation and elimination of postsynaptic dendritic spines of layer-V pyramidal neurons in the mouse frontal association cortex. Here we show that fear conditioning by pairing an auditory cue with a footshock increases the rate of spine elimination. By contrast, fear extinction by repeated presentation of the same auditory cue without a footshock increases the rate of spine formation. The degrees of spine remodelling induced by fear conditioning and extinction strongly correlate with the expression and extinction of conditioned fear responses, respectively. Notably, spine elimination and formation induced by fear conditioning and extinction occur on the same dendritic branches in a cue- and location-specific manner: cue-specific extinction causes formation of dendritic spines within a distance of two micrometres from spines that were eliminated after fear conditioning. Furthermore, reconditioning preferentially induces elimination of dendritic spines that were formed after extinction. Thus, within vastly complex neuronal networks, fear conditioning, extinction and reconditioning lead to opposing changes at the level of individual synapses. These findings also suggest that fear memory traces are partially erased after extinction.

Ultraviolet extinction properties of grains in the interstellar medium

International Nuclear Information System (INIS)

Seab, C.G.

1982-01-01

The IUE satellite has been used to derive UV extinction curves for 58 stars, ranging in spectral type from 06 the A5, and with E(B-V) reddenings from 0.09 to 1.59 mag. The average reddening is 0.63 mag. Anomalous extinction curves were particularly sought in the project. The most striking discovery was the near absence of the 2175 Angstrom extinction feature from the line of sight towards HD 29647 in the Taurus dark cloud. The collection of data has been analyzed in several ways. Patterns are sought in the collection as a whole, in homogeneous subsets of the data, and in relation to diffuse band strengths. Apart from some well-known correlations, only a few weak relationships are found, including a quasi-relationship between the 2175 Angstrom bump and the 4430 Angstrom diffuse band that persists after the basic E(B-V) dependencies have been removed. A search for diffuse bands in the UV was done by stacking 48 of the extinction curves to reduce the noise. The stacked curve showed no evidence of new diffuse bands. To help interpret the anomalous extinction curves, a theoretical simulation of grain processing in interstellar shocks was undertaken. Shock processing was found to cause strong 2175 angstorm bumps and high far UV extinction. Comparison to extinction curves associated with supernova remnants confirms the predictions of strong 2175 Angstrom bumps, and partially confirms the prediction of high far UV extinction. The implications of all of these results are considered for the two most prominent grain models

Medial Prefrontal Cortex Activation Facilitates Re-Extinction of Fear in Rats

Science.gov (United States)

Chang, Chun-hui; Maren, Stephen

2011-01-01

It has been suggested that reduced infralimbic (IL) cortical activity contributes to impairments of fear extinction. We therefore explored whether pharmacological activation of the IL would facilitate extinction under conditions it normally fails (i.e., immediate extinction). Rats received auditory fear conditioning 1 h before extinction training.…

The fossil record of evolution: Analysis of extinction

Science.gov (United States)

Raup, D. M.

1986-01-01

There is increasing evidence that events in space have had direct effects on Earth history and on the history of life on Earth. Nowhere is this more evident than in mass extinction. The biosphere has undergone repeated devastation caused by relatively short-lived environmental stress, with species kill rates up to 80 and 95%. For five of the mass extinctions, geochemical or other evidence was reported suggesting large body impact as the cause of the environmental stress producing the extinctions. It was argued on statistical ground that the major extinction events are uniformly periodic in geological time. If it is true that large body impact is a principal cause of mass extinctions and if the periodicity is real, than a cosmic driving mechanism is inescapable. Paleontological data sets were developed which detail the ranges in geological time of about 4,000 families and 25,000 genera of fossil marine organisms. Analyses to date have concentrated on the most recent 250 million years. Associated with these studies are analyses of other aspects of Earth history which may have signatures indicative of extraterrestrial effects.

Body Size Preference of Marine Animals in Relation to Extinction Selectivity

Science.gov (United States)

Sriram, A.; Idgunji, S.; Heim, N. A.; Payne, J.

2014-12-01

Our project encompasses an extremely specific aspect in relation to the five mass extinctions in geologic history. We asked ourselves whether larger or smaller body sizes would be better suited for surviving a mass extinction. To conduct research for our project, we used the body sizes of 17,172 marine animal genera as our primary data. These animals include echinoderms, arthropods, chordates, mollusks, and brachiopods. These creatures are perfect model organisms in terms of finding data on them because they have an excellent fossil record, and are well documented. We focused on the mean body size of these animals before and after each of the five mass extinctions (end-Ordovician, Late Devonian, end-Permian, end-Triassic, and end-Cretaceous). Our hypothesis was that the average biovolume of animals increased after each of the extinctions, with the mean size being greater after than it was before. Our size data is from the Ellis & Messina Catalogue of Ostracoda and the Treatise on Invertebrate Paleontology. We obtained stratigraphic range data The Treatise and Sepkoski (2002). In our analyses, we compared the mean size of the different animal genera before and after each extinction event. We further partitioned size change across mass extinction boundaries into three categories: the surviving genera, the extinct genera, and the newly originating genera that came about after the extinction. According to our analyses, the mean sizes did not change significantly from the genera living during the stages before the extinctions and after the extinctions. From our results, we can assume that there were not enough major increases in the overall volume of the organisms to warrant a definite conclusion that extinctions lead to larger body sizes. Further support for our findings came from the T-tests in our R code. Only the Cretaceous period showed true evidence for size changing because of the extinction; in this case, the mean size decreased. T-tests for the Cretaceous

Ecological selectivity of the emerging mass extinction in the oceans.

Science.gov (United States)

Payne, Jonathan L; Bush, Andrew M; Heim, Noel A; Knope, Matthew L; McCauley, Douglas J

2016-09-16

To better predict the ecological and evolutionary effects of the emerging biodiversity crisis in the modern oceans, we compared the association between extinction threat and ecological traits in modern marine animals to associations observed during past extinction events using a database of 2497 marine vertebrate and mollusc genera. We find that extinction threat in the modern oceans is strongly associated with large body size, whereas past extinction events were either nonselective or preferentially removed smaller-bodied taxa. Pelagic animals were victimized more than benthic animals during previous mass extinctions but are not preferentially threatened in the modern ocean. The differential importance of large-bodied animals to ecosystem function portends greater future ecological disruption than that caused by similar levels of taxonomic loss in past mass extinction events. Copyright © 2016, American Association for the Advancement of Science.

Diurnal Patterns of Direct Light Extinction in Two Tropical Forest Canopies

Science.gov (United States)

Cushman, K.; Silva, C. E.; Kellner, J. R.

2016-12-01

The extent to which net ecosystem production is light-limited in Neotropical forests is poorly understood. This is due in part to our limited knowledge of how light moves through complex canopies to different layers of leaves, and the extent to which structural changes in canopies modify the amount of light absorbed by the landscape to drive photosynthesis. Systematic diurnal changes in solar angle, leaf angle, and wind speed suggest that patterns of light attenuation change over the course of the day in tropical forests. In this study, we characterize the extinction of direct light through the canopies of two forests in Panama using high-resolution, three-dimensional measurements from a small footprint, discrete return airborne laser scanner mounted on the gondola of a canopy crane. We hypothesized that light penetrates deeper into canopies during the middle of the day because changes in leaf angle by light-saturated leaves temporarily reduce effective canopy leaf area, and because greater wind speeds increase sunflecks. Also, we hypothesized that rates of light extinction are greater in the wetter forest that receives less direct sunlight because light saturation in upper leaves is less prevalent. We collected laser measurements with resolution of approximately 5,000 points per square meter of ground every 90 minutes over the course of one day each at Parque Natural Metropolitano (1740 mm annual rainfall) and Parque Nacional San Lorenzo (3300 mm annual rainfall) during the dry season in April, 2016. Using a voxel-based approach, we compared the actual versus potential distance traveled by laser beams through each volume of the canopy. We fit an exponential model to quantify the rate of light extinction. We found that rates of light extinction vary spatially, temporally, and by site. These results indicate that variation in forest structure changes patterns of light attenuation through the canopy over multiple scales.

Fish extinctions alter nutrient recycling in tropical freshwaters.

Science.gov (United States)

McIntyre, Peter B; Jones, Laura E; Flecker, Alexander S; Vanni, Michael J

2007-03-13

There is increasing evidence that species extinctions jeopardize the functioning of ecosystems. Overfishing and other human influences are reducing the diversity and abundance of fish worldwide, but the ecosystem-level consequences of these changes have not been assessed quantitatively. Recycling of nutrients is one important ecosystem process that is directly influenced by fish. Fish species vary widely in the rates at which they excrete nitrogen and phosphorus; thus, altering fish communities could affect nutrient recycling. Here, we use extensive field data on nutrient recycling rates and population sizes of fish species in a Neotropical river and Lake Tanganyika, Africa, to evaluate the effects of simulated extinctions on nutrient recycling. In both of these species-rich ecosystems, recycling was dominated by relatively few species, but contributions of individual species differed between nitrogen and phosphorus. Alternative extinction scenarios produced widely divergent patterns. Loss of the species targeted by fishermen led to faster declines in nutrient recycling than extinctions in order of rarity, body size, or trophic position. However, when surviving species were allowed to increase after extinctions, these compensatory responses had strong moderating effects even after losing many species. Our results underscore the complexity of predicting the consequences of extinctions from species-rich animal communities. Nevertheless, the importance of exploited species in nutrient recycling suggests that overfishing could have particularly detrimental effects on ecosystem functioning.

Dynamic reorganization of photosynthetic supercomplexes during environmental acclimation

Directory of Open Access Journals (Sweden)

Jun eMinagawa

2013-12-01

Full Text Available Plants and algae have acquired the ability to acclimate to ever-changing environments in order to survive. During photosynthesis, light energy is converted by several membrane protein supercomplexes into electrochemical energy, which is eventually used to assimilate CO2. The efficiency of photosynthesis is modulated by many environmental factors such as quality and quantity of light, temperature, drought, and CO2 concentration, among others. Accumulating evidence indicates that photosynthetic supercomplexes undergo supramolecular reorganization within a short timeframe during acclimation to an environmental change. This reorganization includes state transitions that balance the excitation of photosystem I and II by shuttling peripheral antenna proteins between the two, thermal energy dissipation that occurs at energy-quenching sites within the light-harvesting antenna generated for negative feedback when excess light is absorbed, and cyclic electron flow that is facilitated between photosystem I and the cytochrome bf complex when cells demand more ATP and/or need to activate energy dissipation. This review will highlight the recent findings regarding these environmental acclimation events in model organisms with particular attention to the unicellular green alga C. reinhardtii and with reference to the vascular plant A. thaliana, which offers a glimpse into the dynamic behavior of photosynthetic machineries in nature.

Theoretical investigation of the extinction coefficient of magnetic fluid

Energy Technology Data Exchange (ETDEWEB)

Fang Xiaopeng; Xuan Yimin, E-mail: ymxuan@mail.njust.edu.cn; Li Qiang [Nanjing University of Science and Technology, School of Energy and Power Engineering (China)

2013-05-15

A new theoretical approach for calculating the extinction coefficient of magnetic fluid is proposed, which is based on molecular dynamics (MD) simulation and T-matrix method. By means of this approach, the influence of particle diameter, particle volume fraction, and external magnetic filed on the extinction coefficient of magnetic fluid is investigated. The results show that the extinction coefficient of the magnetic fluid linearly increases with increase in the particle volume fraction. For a given particle volume fraction, the extinction coefficient increases with increase in the particle diameter which varies from 5 to 20 nm. When a uniform external magnetic filed is applied to the magnetic fluid, the extinction coefficient of the magnetic fluid presents an anisotropic feature. These results agree well with the reported experimental results. The proposed approach is applicable to investigating the optical properties of magnetic fluids.

Extinction correction and synchrotron radiation

International Nuclear Information System (INIS)

Suortti, P.

1983-01-01

The primary extinction factor ysub(p) is defined as the ratio of the integrated reflection from a coherently diffracting domain to the integrated kinematical reflection from the same domain. When ysub(p) is larger than 0.5 it may be approximated by ysub(p)= exp[-(αdelta) 2 ], where α is about 0.5 and delta the average size of the coherent domain when measured in units of the extinction length Λ, delta = D/Λ. Transfer equations are applied to symmetrical Laue diffraction, and the reflectivity per unit length, sigma(epsilon) is solved from the measured reflecting ratio as a function of the rocking angle epsilon = theta -thetasub(B). Measurements with conventional x-ray sources are made on single crystal slabs of Be and Si using AgKβ, MoKα 1 and CuKα radiation. The primary extinction factor ysub(p)(epsilon) is solved from a point-by-point comparison of two measurements where the extinction length Λ is changed by varying the polarization and/or wavelength of the x-ray beam. The results show that primary and secondary extinction are strongly correlated, and that the customary assumption of independent size and orientation distributions of crystal mosaics is unjustified. The structure factors for Be and Si show close agreement with other recent measurements and calculations. The limitations of the method are discussed in length, particularly the effects of beam divergences and incoherence of the rays in the crystal. It is concluded that under typical experimental conditions the requirements of the theory are met. Practical limitations arising from the use of characteristic wavelengths and unpolarized radiation prohibit the use of the full potential of the method. The properties of a synchrotron radiation source are compared with a conventional x-ray source, and it is demonstrated that the experimental limitations can be removed by the use of synchrotron radiation. A diffraction experiment with synchrotron radiation is outlined, as well as generalization of the

Post-Retrieval Extinction Attenuates Cocaine Memories

OpenAIRE

Sartor, Gregory C; Aston-Jones, Gary

2013-01-01

Recent studies have shown that post-retrieval extinction training attenuates fear and reward-related memories in both humans and rodents. This noninvasive, behavioral approach has the potential to be used in clinical settings to treat maladaptive memories that underlie several psychiatric disorders, including drug addiction. However, few studies to date have used a post-retrieval extinction approach to attenuate addiction-related memories. In the current study, we attempted to disrupt cocaine...

Accelerated modern human–induced species losses: Entering the sixth mass extinction

Science.gov (United States)

Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; García, Andrés; Pringle, Robert M.; Palmer, Todd M.

2015-01-01

The oft-repeated claim that Earth’s biota is entering a sixth “mass extinction” depends on clearly demonstrating that current extinction rates are far above the “background” rates prevailing between the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 100 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing. PMID:26601195

A scenario for impacts of water availability loss due to climate change on riverine fish extinction rates

NARCIS (Netherlands)

Tedesco, P.A.; Oberdorff, T.; Cornu, J.-F.; Beauchard, O.; Brosse, S.; Dürr, H.H.; Grenouillet, G.; Leprieur, F.; Tisseuil, C.; Zaiss, R.; Hugueny, B.

2013-01-01

1. Current models estimating impact of habitat loss on biodiversity in the face of global climate change usually project only percentages of species committed to extinction' on an uncertain time-scale. Here, we show that this limitation can be overcome using an empirically derived background

THE MID-INFRARED EXTINCTION LAW IN THE LARGE MAGELLANIC CLOUD

International Nuclear Information System (INIS)

Gao, Jian; Jiang, B. W.; Xue, M. Y.; Li, Aigen

2013-01-01

Based on photometric data from the Spitzer/SAGE survey, using red giants as extinction tracers, the mid-infrared (MIR) extinction laws in the Large Magellanic Cloud (LMC) are derived for the first time in the form of A λ /A K S . This quantity refers to the extinction in the four Infrared Array Camera (IRAC) bands (i.e., [3.6], [4.5], [5.8], and [8.0] μm) relative to the Two Micron All Sky Survey K S band at 2.16 μm. We obtain the near-infrared extinction coefficient to be E(J – H)/E(H – K S ) ≈ 1.29 ± 0.04 and E(J – K S )/E(H – K S ) ≈ 1.94 ± 0.04. The wavelength dependence of the MIR extinction A λ /A K S in the LMC varies from one sightline to another. The overall mean MIR extinction is A [3.6] /A K S ∼0.72±0.03, A [4.5] /A K S ∼0.94±0.03, A [5.8] /A K S ∼0.58±0.04, and A [8.0] /A K S ∼0.62±0.05. Except for the extinction in the IRAC [4.5] μm band, which may be contaminated by the 4.6 μm CO gas absorption of red giants used to trace LMC extinction, the extinction in the other three IRAC bands show a flat curve, close to the Milky Way R V = 5.5 model extinction curve, where R V is the optical total-to-selective extinction ratio. The possible systematic bias caused by the correlated uncertainties of K S – λ and J – K S is explored in terms of Monte Carlo simulations. We find that this bias could lead to an overestimation of A λ /A K S in the MIR

Inhibition of Rac1 activity in the hippocampus impaired extinction of contextual fear.

Science.gov (United States)

Jiang, Lizhu; Mao, Rongrong; Tong, Jianbin; Li, Jinnan; Chai, Anping; Zhou, Qixin; Yang, Yuexiong; Wang, Liping; Li, Lingjiang; Xu, Lin

2016-10-01

Promoting extinction of fear memory is the main treatment of fear disorders, especially post-traumatic stress disorder (PTSD). However, fear extinction is often incomplete in these patients. Our previous study had shown that Rac1 activity in hippocampus plays a crucial role in the learning of contextual fear memory in rats. Here, we further investigated whether Rac1 activity also modulated the extinction of contextual fear memory. We found that massed extinction obviously upregulated hippocampal Rac1 activity and induced long-term extinction of contextual fear in rats. Intrahippocampal injection of the Rac1 inhibitor NSC23766 prevents extinction of contextual fear in massed extinction training rats. In contrast, long-spaced extinction downregulated Rac1 activity and caused less extinction. And Rac1 activator CN04-A promotes extinction of contextual fear in long-spaced extinction rats. Our study demonstrates that inhibition of Rac1 activity in the hippocampus impaired extinction of contextual fear, suggesting that modulating Rac1 activity of the hippocampus may be promising therapy of fear disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

On the anomaly of the far UV extinction law in the 30 Doradus region

International Nuclear Information System (INIS)

Koornneef, J.

1976-01-01

Area-integrated ultraviolet observations made with the Netherlands Astronomical Satellite (ANS), of about 800 fields in a 0.7 square degree region around the giant HII region 30 Doradus in the Large Magellanic Cloud are discussed. The five-channel ANS photometric system is shown to be information redundant in the present application; the observations can therefore be discussed in terms of only two parameters: visual brightness and a temperature parameter (colour). A colour-brightness diagram is presented for about 600 fields with good quality measurements with the conclusion that most of the spread in colour is caused by differential extinction. By various independent methods it was found that the 2200 A-feature is deficient by a factor of three on a logarithmic scale relative to the average galactic extinction law

Relapse processes after the extinction of instrumental learning: Renewal, resurgence, and reacquisition

Science.gov (United States)

Bouton, Mark E.; Winterbauer, Neil E.; Todd, Travis P.

2012-01-01

It is widely recognized that extinction (the procedure in which a Pavlovian conditioned stimulus or an instrumental action is repeatedly presented without its reinforcer) weakens behavior without erasing the original learning. Most of the experiments that support this claim have focused on several “relapse” effects that occur after Pavlovian extinction, which collectively suggest that the original learning is saved through extinction. However, although such effects do occur after instrumental extinction, they have not been explored there in as much detail. This article reviews recent research in our laboratory that has investigated three relapse effects that occur after the extinction of instrumental (operant) learning. In renewal, responding returns after extinction when the behavior is tested in a different context; in resurgence, responding recovers when a second response that has been reinforced during extinction of the first is itself put on extinction; and in rapid reacquisition, extinguished responding returns rapidly when the response is reinforced again. The results provide new insights into extinction and relapse, and are consistent with principles that have been developed to explain extinction and relapse as they occur after Pavlovian conditioning. Extinction of instrumental learning, like Pavlovian learning, involves new learning that is relatively dependent on the context for expression. PMID:22450305

Variation in extinction risk among birds: chance or evolutionary predisposition?

Science.gov (United States)

Bennett, P. M.; Owens, I. P. F.

1997-01-01

Collar et al. (1994) estimate that of the 9,672 extant species of bird, 1,111 are threatened by extinction. Here, we test whether these threatened species are simply a random sample of birds, or whether there is something about their biology that predisposes them to extinction. We ask three specific questions. First, is extinction risk randomly distributed among families? Second, which families, if any, contain more, or less, threatened species than would be expected by chance? Third, is variation between taxa in extinction risk associated with variation in either body size or fecundity? Extinction risk is not randomly distributed among families. The families which contain significantly more threatened species than expected are the parrots (Psittacidae), pheasants and allies (Phasianidae), albatrosses and allies (Procellariidae), rails (Rallidae), cranes (Gruidae), cracids (Cracidae), megapodes (Megapodidae) and pigeons (Columbidae). The only family which contains significantly fewer threatened species than expected is the woodpeckers (Picidae). Extinction risk is also not distributed randomly with respect to fecundity or body size. Once phylogeny has been controlled for, increases in extinction risk are independently associated with increases in body size and decreases in fecundity. We suggest that this is because low rates of fecundity, which evolved many tens of millions of years ago, predisposed certain lineages to extinction. Low-fecundity populations take longer to recover if they are reduced to small sizes and are, therefore, more likely to go extinct if an external force causes an increase in the rate of mortality, thereby perturbing the natural balance between fecundity and mortality.